Transport of IgG across the blood-luminal barrier of the male reproductive tract of the rat and the effect of estradiol administration on reabsorption of fluid and IgG by the epididymal ducts

In rats immunized systemically with tetanus toxoid the concentration of specific anti-tetanus-toxoid-specific IgG in fluid from the rete testis and cauda epididymidis were respectively 0.6% and 1.4% the concentration in blood serum. The extratesticular duct system reabsorbed 97% of the IgG and 99% of the fluid leaving the rete, but estradiol administration affected the site of reabsorption. In untreated rats, the ductuli efferentes reabsorbed 94% of the IgG and 96% of the fluid leaving the rete, whereas estradiol-treated rats reabsorbed 83% of the IgG and 86% of the fluid, and the ductus epididymidis fully compensated for these different effects of estradiol on the ductuli efferentes. The concentrations of IgG in secretions of the seminal vesicles and prostate gland were lower (0.1% and 0.3% respectively of the titers in blood serum) than in fluids from the extratesticular ducts, and were not affected by the administration of estradiol. RT-PCR showed that Fcgrt (neonatal Fc receptor, also known as FcRn) is expressed in the reproductive ducts, where IgG is probably transported across epithelium, being particularly strong in the ductuli efferentes (where most IgG was reabsorbed) and distal caput epididymidis. It is concluded that IgG enters the rete testis and is concentrated only 2.5-fold along the extratesticular duct system, unlike spermatozoa, which are concentrated 95-fold. Further, the ductus epididymidis can recognize and compensate for changes in function of the ductuli efferentes.     

Changes in the composition of the excurrent duct system of the rat testis during postnatal development.

The gross composition of the testicular excurrent duct system of the rat was examined and compared along the length of the duct and with samples of testis, bladder and liver. Changes in composition with age were examined by analysing tissue from animals at postnatal ages of 19, 36, 48, 60, 90 and 120 days. In adult animals, testicular tissue was characterized by having the lowest dry weight, accompanied by low levels of total protein, lipid, RNA and glycogen; DNA, phospholipids and sialic acid were at levels similar to other tissues. A high proportion of the total protein was soluble. The ductuli efferentes plus initial segment of the epididymis were characterized by high levels of total lipid. The caput epididymidis contained a low level of total protein but a high level of acid-soluble phosphorus. The cauda epididymidis had a low dry weight and low levels of total protein, soluble protein, and lipid, but high levels of acid-soluble phosphorus, DNA and sialic acid. The ductus deferens contained small amounts of RNA and DNA but had a high dry weight, high total protein, soluble protein and glycogen. Several trends were apparent with increasing age. Dry weight increased in the ductuli efferentes plus initial segment, whilst total protein decreased in the caput and cauda epididymidis. Total lipid increased in the ductuli efferentes plus initial segment and acid-soluble phosphorus and sialic acid increased in all other segments of the excurrent duct system. In all segments the content of RNA and DNA decreased as the animals matured. The concentration of calcium and magnesium in the excurrent duct system was not significantly different from those levels found in the liver. High levels of spermine and spermidine were confirmed in the prostate, and were also detected in the testis, caput epididymidis and cauda epididymidis, but at a much lower concentration.     

Changes in protein composition of the luminal fluids along the epididymis of the tammar, Macropus eugenii

Micropuncture samples of luminal fluid were collected from the rete testis and along the epididymis. Quantitative analyses showed that the ductuli efferentes reabsorb about half the protein leaving the testis. Considerable protein is secreted by the caput epididymidis (initial segment) and there is a net loss of protein from the corpus and cauda epididymidis. Denatured, polyacrylamide gel electrophoresis showed that there are 5 proteins in rete testis fluid which are not present in blood (Mr of 14,700, 22,800, 24,100, 43,000 and 44,800). One of these proteins (Mr 14,700) is lost from plasma in the ductuli efferentes and 2 (Mr 43,200 and 44,800) are lost in the corpus epididymidis. Twelve proteins appear in the epididymal plasma and are not present in rete testis fluid or blood: 6 appear in the caput epididymidis (Mr 30,000, 31,000, 32,300, 17,400, 18,700 and 21,400), 3 in the corpus epididymidis (Mr 12,800, 39,800 and 90,600) and 3 in the cauda epididymidis (Mr 10,900, 56,300 and 63,000). A protein with the same molecular weight as a blood protein (149,500) accumulates in the corpus and cauda epididymidis. None of the samples of luminal fluid contained particulate matter other than spermatozoa, indicating that the tammar is a useful animal for micropuncture studies.     

Resorption versus secretion in the rat epididymis

Micropuncture samples were taken from the rete testis, caput epididymidis and cauda epididymidis of anaesthetized adult rats and assayed for total protein, sodium and potassium concentrations. Intraluminal sperm concentrations were determined and used to calculate the amount of fluid resorbed from the efferent duct and epididymal lumen. It was demonstrated that large amounts of protein (30.2 mg/ml cauda volume) and sodium (241.8 mequiv./l) and smaller amounts of potassium (19.4 mequiv./l) are resorbed from the rat epididymal lumen between the caput and corpus epididymidis. This occurs despite increases in intraluminal concentrations of protein (from 22 to 28 mg/ml) and potassium (from 16 to 50 mequiv./l). Resorption is an important aspect of epididymal control of the intraluminal environment.     

Microprobe analysis of Na,K, Cl,P, S,Ca, Mg and H2O in frozen-hydrated sections of anterior caeca of the locust, Schistocerca gregaria

Electron probe X-ray microanalysis of frozen-hydrated sections was carried out for sodium, potassium, chlorine, calcium, magnesium, sulphur, phosphorus and water concentrations in the lumen and epithelial cells of freshly-fed adult female desert locusts, and in blood of fed and starved locusts.Sodium and chloride were found to be at a much lower level in the lumen and cells than potassium, and at a much higher level in the blood. The luminal folds were plugged with a dense organic matrix, presumed to be polyanionic glycosaminoglycans, which appeared to restrict access of charged moieties of the absorptive sites. The data were consistent with a model of caecal fluid absorption in which a passive flux of potassium from lumen to blood, possibly assisted by an active absorption of chloride, drives fluid into the blood. Unlike the case of the vertebrate intestine, active absorption of sodium from the lumen would not contribute significantly to the fluid transport in vivo.     

A Comparative Study on the Chemical Composition of Plasma from the Cauda Epididymidis,Semen Fractions,and Whole Semen in Boars

A comparative study was carried out on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen of boars. A total of 22 boars were used in this study. The boars, which ranged in age from 8 to 14 months, were of Swedish Landrace and Swedish Yorkshire breed. All boars used presented a normal semen picture. A dummy sow and an artificial vagina were employed for semen collection. The semen was collected as whole semen and as semen fractions in 10 nil volumes. The contents of the cauda epididymidis was removed post mortem. The following parameters were investigated: sperm concentration, dry weight of spermatozoa and of seminal plasma, osmotic pressure, sodium, potassium, chloride, inorganic phosphorus, calcium, magnesium, total protein, GOT, GPT, and alkaline phosphatase in seminal plasma. Paper electrophoresis was carried out on seminal plasma. Tlxe results of the analysis are summarized in Tables 1–6. The sperm concentration was approximately 3.2 mill./mm3 in the cauda epididymidis, 1 mill./mm3 in the sperm-richest fraction (II) and 0.25 mill./mm3 in whole semen. The dry weight (expressed in per cent dry matter) of spermatozoa was highest in the cauda epididymidis (25.47 %), showing a tendency to decreasing in semen fractions I—IV and was lowest in whole semen (15.29 %). The per cent dry weight in plasma was higher in the cauda epididymidis (4.56 %) than in semen fraction I (2.20 %). In semen fractions I—IV the per cent dry weight rose from 2.20 (U to 4.51 % and reached the level of approximately 3.80 % in the sperm-free fractions V—VII. The osmotic pressure was significantly higher in the cauda epidi-dymal plasma than in the whole seminal plasma or the seminal plasma fractions. The same phenomenon was observed in a boar where the cauda epididymal content was collected in vivo from a patent established fistula. There appears to be a connection between the per cent dry weight of spermatozoa and the osmotic pressure, which means that the per cent dry weight of the cauda epididymal spermatozoa decreases when mixed with the accessory gland secretions, which have a lower osmotic pressure. The fall in per cent dry weights is thought to be caused by an intake of water. The amount of sodium, chloride and magnesium was higher in ejaculated seminal plasma than in cauda epididymal plasma. The reverse was true for inorganic phosphorus and potassium. Moreover the sperm-free fractions contained more sodium, chlorides and magnesium than the sperm-containing fractions, while the concentration of potassium and inorganic phosphorus was comparatively higher in the sperm-containing fractions. A connection is apparent between sperm concentration and the potassium, inorganic phosphorus and magnesium levels. Statistical analysis of the values of chloride and magnesium revealed significant differences between individual boars for most of the semen fractions. The concentration of plasma proteins in the cauda epididymidis was approximately the same as in whole semen and in the semen fractions except for fraction I, which contained a relatively low concentration. As regards total protein there were significant differences between individual boars in most of the semen fractions as well. The paper electrophoretic pattern of epididymal plasma was different from that of semen plasma. Thus there were three or four distinct components in the cauda epididymidis numbered 1, 2, 3, and 4, and three distinct components in whole seminal plasma numbered 3, 4, and 5, while the sperm-richest semen fractions contained four components (2, 3, 4, and 5) and the others three components, namely 3, 4, and 5. The level of GOT was high in the cautlu cpiflidymill contents (99.1 i. u./ml) compared with that for whole seminal plasma (99.1 i.u/ml). In semen fractions there was a clear positive correlation between the level of GOT and the sperm concentration. The GPT concentration wis as a whole low and. in contrast to GOT. somewhat higher in the sperm-free fractions than in the sperm-containing fractions. The concentration of alkaline phosphatase was very high in cauda epididymal plasma (31,463 i. u./ml) as well as in the sperm-rich fractions (e.g. 7,096 i. u./ml in fraction II). Preliminary investigation has moreover revealed a very low alkaline phosphatase concentration in seminal plasma of vasectomized boars, which condition suggests thai the main origin for alkaline phosphatase in boars is the testis and epididymis.     

Effect of various chloride salts on the utilization of phosphorus, calcium, and magnesium

Only part of the effect of dietary protein on urinary calcium excretion can be ascribed to sulfur amino acids. We hypothesized that chloride, another factor often associated with isolated proteins, and another amino acid, lysine, affect utilization of calcium. The effects of supplemental dietary chloride, inorganic or organic, on calcium, phosphorus, and magnesium utilization were studied in two rat studies. Weanling Sprague-Dawley rats were fed semi-purified diets that contained moderate (1.8 mg Cl/g diet) or supplemental (15.5 mg Cl/g diet) chloride as sodium chloride, potassium chloride, or lysine monohydrochloride with or without calcium carbonate for 56 or 119 days. Rats fed supplemental sodium chloride or potassium chloride had higher urinary phosphorus excretion, more efficient phosphorus absorption, but unchanged tissue phosphorus levels after 7 and 16 weeks of dietary treatment as compared to rats fed moderate chloride. Rats fed supplemental sodium chloride or potassium chloride excreted more calcium in urine at 7 weeks and absorbed calcium less efficiently at 16 weeks. Tissue calcium concentrations were unaffected, but total tibia magnesium and plasma magnesium concentrations were lower in rats fed supplemental sodium chloride or potassium chloride than those fed moderate chloride. Lysine chloride with or without additional calcium elevated urinary calcium excretion even more than sodium chloride and potassium chloride ingestion. Rats fed lysine chloride with supplemental calcium had smaller apparent absorption and urinary losses of phosphorus and magnesium after 16 weeks and lower tibia and plasma magnesium concentrations than rats fed lysine chloride.     

Ion concentrations in oviduct and uterine fluid and blood serum during the estrous cycle in the bovine

In the bovine up to 40% of embryos die before implantation but despite the importance of ions in oviduct and uterine fluid formation and in gamete, zygote and early embryo development there is very little published information on the ion concentrations of oviduct or uterine fluid. The free anions chloride, phosphate and sulphate and the free cations sodium, calcium, magnesium and potassium were measured in oviduct fluid on days 0, 2, 4 and 6 and in uterine fluid on days 6, 8 and 14 and in corresponding blood samples. Oviduct and uterine fluids were collected in situ. Sodium was 25-fold higher than potassium and 80-fold higher than the other ions and chloride was 10-fold higher than potassium and 40-fold higher than the other ions in oviduct and uterine fluid. Phosphate, sulphate, magnesium, potassium and calcium were at lower concentrations in all fluids. Oviduct calcium and sodium were higher on day 0 than other days. The most striking uterine differences were the higher potassium and lower chloride, sodium and magnesium on day 14 than other days. There were significant positive associations between oviduct and blood chloride, sulphate, magnesium and calcium while only uterine sulphate was positively related to its blood concentration. There was no relationship between fluid secretion rate and no association between the concentrations of systemic progesterone or oestradiol and any ion in oviduct or uterine fluid. The different concentrations and associations between ions in the oviduct, uterus and blood suggest a differential regulation of ion secretion by the oviduct and uterine epithelia.     

Structure and functions of the genital ducts of the male Port Jackson shark,Heterodontus portusjacksoni

Synopsis The genital ducts ofHeterodontus portusjacksoni consist of the sperm carrying ducts (the rete testis, ductuli efferentes, and initial and terminal segments of the ductus epididymidis) and the Leydig glands (anterior opisthonephros). The ducts are lined by a ciliated epithelium which maintains a barrier to the transport of solute between blood and the lumen of the duct. Spermatozoa, Sertoli cell bodies, Sertoli cell cytoplasts and cellular debris are released from spermatocysts into the longitudinal canal of the rete testis. However, only the Sertoli cell cytoplasts persist throughout the sperm ducts. The epithelia lining the initial segment of the ductus epididymidis and secretory tubules of the Leydig glands are specialized for protein secretion and (particularly the Leydig glands) must be the main source of luminal protein in the ductus epididymidis. The epithelium lining the terminal segment of the ductus epididymidis also secretes protein, reabsorbs fluid and sodium, and may carry out heterophagic digestion. Spermatozoa develop the capacity for motility in the extratesticular sperm ducts, but do not undergo structural changes. However, they form spherical bundles in the terminal segment of the ductus epididymidis. It is suggested that the reduction in ratio of sodium:potassium from 48:8 in the ductuli efferentes to 3:4 in the distal end of the terminal segment of the ductus epididymidis may favour sperm survival.     

Maturation and regulation of the motility of spermatozoa in the epididymis of the tammar wallaby (Macropus eugenii).

Demembranated spermatozoa from the rete testis developed vigorous flagellation when reactivated with ATP, but showed no forward progression such as that seen in samples from the cauda epididymidis. The proportion of spermatozoa that were reactivated was smaller for samples from the rete testis than from the cauda epididymidis. Studies in vitro of undiluted micropuncture samples from the epididymis indicated that the activity of spermatozoa is suppressed as they develop the capacity for motility. However, as spermatozoa spontaneously became activated during the collection or subsequent incubation of undiluted samples, it was concluded that the suppressive action is labile. The activity of spermatozoa in vitro was examined in diluted samples from the cauda epididymidis. A concentration of 2.5 mmol extracellular calcium/l was better than lower concentrations. Diluents at pH 5.5 completely inhibited sperm motility when they contained 20 mmol lactate/l (but not glutamate) and the effect was reversed by readjusting the diluent to pH 7.4. However, lactate was not considered to suppress sperm motility in situ, as the plasma from the cauda epididymidis contained only 2.7 +/- 0.5 mmol lactate/l. There was no effect of sodium concentration (1 and 115 mmol/l), pH (5.5 and 7.4) or amiloride (0 and 1 mmol/l) on sperm motility, indicating that motility is not dependent on the concentration of sodium above 1 mmol/l or on a sodium-proton exchange system. The relative viscosity of plasma from the cauda epididymidis did not affect the motility of spermatozoa.     

The concentration of carnitine in the luminal fluid of the testis and epididymis of the rat and some other mammals.

Luminal fluid was collected by micropuncture techniques from the testis and epididymis of the rat, hamster, rabbit, boar and ram and the concentration of free L-carnitine in the fluid was estimated using enzymic methods. Carnitine was present in the testicular fluid of the rat in concentrations less than 1 mM but increased down the epididymis to reach 53 mM in luminal fluid from the cauda epididymidis, approximately 2000 times higher than in blood plasma. A high concentration was first found in the luminal fluid from the distal caput epididymidis, at about the point where the spermatozoa become motile. Carnitine was also present in the epididymal luminal fluid of the other species studied; the amounts were not as high as those in the rat but were still higher than those in blood plasma.     

Effects of controlled pH on organic and inorganic composition in haemolymph,epidermal tissue and cuticle of mud crab Scylla serrata

Analysis of organic and inorganic compounds in plasma, epidermal tissue and cuticle were accomplished in the intermolt (C3 stage) of crab Scylla serrata incubated in different pH media. Significant changes with similar trends for protein, carbohydrates, glycosaminoglycans (GAG), sulphur, calcium, magnesium, potassium, phosphorus and copper in the plasma suggested higher dissolution in an acidic medium while the deposition increased in alkaline medium. Similar decreases in protein, carbohydrate and GAG in the epidermal compartment were observed from pH 4 to pH 12. However, significantly higher contents of sodium, chloride, potassium, phosphorus, magnesium, sulphur and copper were measured at pH 7.5 with a symmetrical decrease profile in both acidic and alkaline media, resulting from synergistic effects in the osmotic regulation. Clear changes in calcium concentrations were observed with a sharp increase from lower contents at pH 7.5 to higher at pH 12. In the cuticle, the acidic condition induced a significant dissolution of HCl-protein, GAG, calcium and magnesium contents. On the other hand, the alkaline condition induced a significant decrease in carbohydrate, calcium, chloride, sulphur and potassium. A reduction trend is seen for NaOH and H(2)O-protein contents in the cuticle. These observations suggest that GAG and HCl-protein might constitute the most soluble fraction with high affinity for calcium binding and easily removed in acidic conditions. Additionally, it is possible to speculate that the carbohydrates associated with the NaOH and H(2)O-proteins may form an interface between the soluble matrix fraction and the chitin framework. Sulphur groups seem to present a strong linkage role in this interface fraction, maybe only broken by a specific enzyme in extreme alkaline conditions with subsequent release of significant calcium from the shell.     

Immunolocalization and concentrations of inhibin alpha in the ovine testis and excurrent duct system

Inhibin was localized in the ovine testis, excurrent ducts, and accessory sex glands by using a rabbit antiserum against a synthetic polypeptide representing the first 30 amino acids of porcine inhibin alpha-subunit. Concentrations of inhibin in fluids entering and leaving the epididymis also were determined in a radioimmunoassay using the same antibody. In the testis, immunostaining of inhibin was conspicuous in the seminiferous epithelium. Leydig cells occasionally were stained and the tunica media of blood vessels always was stained. Intense staining was observed in the epithelia lining the rete testis and ductuli efferentes. Staining also was intense in the epithelium of the initial segment and proximal caput epididymidis, and became less intense along the length of the epididymis. These observations were consistent with concentrations of inhibin in rete testis fluid (8.2 pmol/ml) entering the ductuli efferentes and in cauda epididymal plasma (0.67 pmol/ml) leaving the epididymis. Epithelia of ampullary and vesicular glands and of some prostatic acini were positively stained, but bulbourethral glands were never stained. Adrenal cortex, some proximal convoluted tubules in the kidney, and transitional epithelium of the urethra also were stained. Based on radioimmunoassay data and fluid flow rates for the ram, it was concluded that almost all of the 328 pmol inhibin that enters the ductuli efferentes daily is endocytosed in the proximal parts of the excurrent duct system. The physiological role(s) for inhibin, or inhibin-like peptides, in the excurrent duct system remains speculative.     

Major contribution of epididymis to alpha-glucosidase content of ram seminal plasma

Acid alpha-glucosidase and L-carnitine (a well-known epididymal marker) were measured in rete testis and epididymal fluids of adult male rams. These fluids were collected by selective catheterization or by a micropuncture technique, respectively. Both parameters remained at a low and constant level in rete testis and all along caput and corpus epididymidis. Then they increased at equivalent rates in cauda epididymidis to much higher levels than those in seminal plasma (5 mU/mg protein and 10 mM, respectively). An optimum pH study of alpha-glucosidase activity in these fluids showed two well-separated peaks in rete testis and caput epididymal fluids around pH 4 and 7, respectively, but only a single peak at pH 4 in cauda epididymidis that was comparable to the one in seminal plasma. Sucrose density gradient fractions analyzed for their enzyme content in the absence or presence of sodium dodecyl sulfate (1% w/v), a selective inhibitor of acid alpha-glucosidase activity, allowed the demonstration of two enzyme forms at pH 6.8 in rete testis fluid sedimenting in the 7S and 4S regions of the gradient, while a unique 4S form was encountered in cauda epididymidis and in seminal plasma. Although the fate of the minor 7S component of the rete testis fluid in its epididymal transit is presently unknown, similarities between the enzyme in cauda epididymidis and seminal plasma are strong enough to support the hypothesis that epididymis contributes primarily to the acid alpha-glucosidase content of ram seminal plasma.     

Sulphur and phosphorus requirements of Curvularia pallescens Boed

The effect of different sulphur and phosphorus compounds on the growth and sporulation ofCurvularia pallescens Boed. has been studied. Nine different sulphur sources were tried but among them only magnesium sulphate yielded the best dry weight of the fungus. Zinc sulphate, sodium sulphate, sodium thiosulphate, potassium sulphate and calcium sulphate supported good growth. Poor growth was recorded on sodium bisulphite, ammonium sulphate, sodium sulphide and control. Sporulation was excellent on magnesium sulphate. It was good on zinc sulphate, sodium sulphate and potassium sulphate. On sodium thiosulphate, calcium sulphate, sodium bisulphite and control it was fair. Sodium sulphide and ammonium sulphate had inhibitory effect as sporulation was poor and nil on these two compounds respectively.Six phosphorus compounds were studied. Tripotassium phosphate gave best growth and excellent sporulation. Good growth and excellent sporulation was recorded on monobasic potassium phosphate and magnesium phosphate. Growth and sporulation were good on dibasic potassium phosphate and sodium dihydrogen phosphate. Ammonium phosphate was poorly utilized.     

Sperm maturation, fluid transport, and secretion and absorption of protein in the epididymis of the echidna, Tachyglossus aculeatus

Extratesticular sperm maturation in the echidna mainly occurs in the initial segment of the ductus epididymidis. The process involves the development of motility, migration and loss of the cytoplasmic droplet, a decrease in permeability to Congo red and the formation of sperm bundles. The spermatozoa are supported in the bundles by a matrix of electron-dense material; the bundles are very motile is undiluted samples of luminal fluids. Micropuncture studies of anaesthetized echidnas showed that the ductuli efferentes absorb 74% of the fluid and 46% of the soluble protein that enters them. The initial segment of the ductus epididymidis absorbs 83% of the fluid which enters it, and its secretions increase the concentration of protein in luminal fluid by 107%. Denatured, linear-gradient polyacrylamide gel electrophoresis of micropuncture samples showed that 1 protein (apparent M4 = 100 500) which is not present in blood plasma is present in rete testis fluid, and a glycoprotein which is present in rete testis fluid (apparent Mr = 78500) is absorbed by the ductuli efferentes. Six proteins which are not present in blood plasma are secreted into the initial segment of the ductus epididymidis; 5 are glycoproteins (apparent Mr = 48500, 39000, 32000, 20500 and 19000) and one (apparent Mr = 82500) is not. The most prominent electrophoresis bands corresponded to the glycoproteins with apparent molecular weights of 48500, 20500 and 19000.     

Sodium, potassium, calcium, magnesium, zinc, citrate and chloride content of human prostatic and seminal fluid

The ionic composition of human prostatic fluid varied greatly between individuals, reflecting the secretory activity of the gland and the presence or absence of prostatic inflammatory disease. In normal prostatic fluid the major anion was citrate, while chloride concentrations were lower. Their counterions were mainly sodium and potassium, together with calcium, magnesium and zinc. Prostatic secretions from men with prostatitis comprised mainly sodium and chloride. The electrolytes were closely correlated to each other (except for sodium, which was essentially invariant at about 145 nm). The molar changes per mole of citrate were about 0.52, potassium; -0.53, chloride; 0.17, calcium; 0.14, magnesium; and 0.09, zinc. The pH was also associated with citrate, decreasing from 8.0 to 6.2 as the citrate increased. These various ionic changes can be explained as responses to citrate secretion, without the need to propose specific transport mechanisms for the other ions measured. The marked effect of prostatic inflammation on the composition of prostatic fluid can be seen as being due mainly to decreased secretion rather than active modification.     

Galactosyltransferase, pyrophosphatase and phosphatase activities in luminal plasma of the cauda epididymidis and in the rete testis fluid of some mammals

Galactosyltransferase activity was measured in the luminal plasma of the cauda epididymidis of mice, rats, rabbits, rams and boars, and in the rete testis fluid of rams and boars. The activities of nucleotide pyrophosphatase and alkaline phosphatase, which compete with galactosyltransferase for substrate, were also determined. In these species, galactosyltransferase activity in the luminal plasma of the cauda epididymidis was similar when the inhibitory effect of pyrophosphatase and phosphatase was minimized by assay conditions. However, under assay conditions that did not minimize the effect of these enzymes, the galactosyltransferase activities of these species were very different and were inversely correlated with the activities of pyrophosphatase and phosphatase. The ratio of galactosyltransferase activity to pyrophosphatase and phosphatase activity was much higher in the rete testis fluid than in the luminal plasma of the cauda epididymidis in both rams and boars. In rams, galactosyltransferase in the luminal plasma of the cauda epididymidis was more heat resistant than that in serum. These results suggest that there is a species difference in the availability of galactosyltransferase activity in the luminal plasma of the cauda epididymidis and that in some species, galactosyltransferase in the luminal fluid is unlikely to have any function. The results are also discussed with respect to the possible function of galactosyltransferase, pyrophosphatase and phosphatase in epididymal luminal plasma and rete testis fluid.     

Influence of Medetomidine on Acid-base Balance and Urine Excretion in Goats

Seven goats were given medetomidine 5 μg/kg as an iv bolus injection. Venous blood samples were taken repeatedly and urine was collected continuously via a catheter up to 7h after the injection. Medetomidine caused deep clinical sedation. Base excess, pH and PCO2 in venous blood rose after medetomidine administration. There were no significant changes in plasma concentrations of sodium, calcium, magnesium, creatinine or osmolality, whereas potassium and bicarbonate concentrations increased, and phosphate and chloride decreased. Medetomidine increased plasma glucose concentration, and in 4 of 7 goats glucose could also be detected in urine. Medetomidine did not influence urine flow rate, free water clearance, bicarbonate and phosphate excretion or pH, but renal chloride, sodium, potassium, calcium, magnesium and creatinine excretion were reduced. The results suggest that the metabolic alkalosis recorded after medetomidine administration is not caused by increased renal acid excretion.     

Fluid secretion by isolated Malpighian tubules of the housefly Musca domestica

The Malpighian tubules of Musca domestica secrete a fluid with a high concentration of potassium and low concentrations of sodium, calcium, magnesium and chloride compared with the isolating medium.Low secretion rates are produced by low medium potassium concentrations (< 7 mM), with low sodium concentrations (up to 5 mM) increasing secretion; higher potassium concentrations produce higher secretion rates whilst higher sodium concentrations have no further effect. Calcium and magnesium are essential for secretion.The rate of tubule secretion is inversely proportional to the osmotic pressure of the isolating medium and the osmotic pressure of the secreted fluid is slightly hyper-osmotic to the medium over a range of medium osmotic pressures.The metabolic inhibitors cyanide, iodoacetate and 2,4-dinitrophenol inhibit secretion: Cu²⁺ ions, arsenate and ouabain have no effect whereas ethacrynic acid abolishes secretion. 5-hydroxytryptamine, cycle AMP and theophylline have no effect on secretion. Sodium thiocyanate stimulates fluid secretion and increases the osmotic pressure and the concentration of sodium and chloride, but not potassium, in the secreted fluid.