Urease activity in the contents and tissues of the sheep, pig and chicken gastrointestinal apparatus.

Urease activity, expressed as mg N-NH3/g dry weight per 30 min at 25 degrees C, was determined in the various parts of the sheep, chicken and pig digestive apparatus. The results were as follows. Sheep: contents--rumen 1.25"/-0.09, reticulum 0.78+/-0.02, omasum 0.44+/-0.02, abomasum 0.002+/-0.001, duodenum 0.003+/-0.001, jejunum 0.18+/-0.03, ileum 0.42+/-0.03, caecum 1.34+/-0.11, colon 0.76+/-0.08, walls-rumen 0.88+/-0.16, reticulum 0.38+/-0.04, omasum 0.11+/-0.02, abomasum 0.01+/-0.002, ileum 0.092+/-0.01, caecum 0.14+/-0.03, colon 0.16+/-0.02. Chicken: contents--jejunum 0.028+/-0.009, ileum 0.043+/-0.013, caecum 0.17+/-0.03, colon and cloaca 0.04+/-0.013. Pigs: contents--jejunum 0.02+/-0.01, ileum 0.14+/-0.08, caecum 0.62+-0.12, colon 0.43+/-0.06. No urease activity was found in the walls of the digestive apparatus or the contents of the duodenum in chickens, or in the walls of the stomach and intestine and the contents of the duodenum in pigs. The results show that urease activity in the digestive apparatus of pigs and poultry is lower than in sheep. Inadequate urease activity in the digestive apparatus explains why chickens and pigs are significantly less capable than ruminants of utilizing urea nitrogen as a substitute for some of the protein in the diet.     

A morphometric analysis of the corpus luteum of the cow during the estrous cycle and early pregnancy

Corpora lutea were collected from cows on Days 6, 8, 10, 12, 14, 16, 18 and 19 of the estrous cycle and early pregnancy (n=2/d) and were examined by light microscopy. Mean lutein cell diameter was significantly (P<0.05) greater in pregnant than in cyclic cows on Days 6, 8, 10, 12, 16, 18 and 19 (cyclic versus pregnant: Day 6: 13.9 +/- 0.22 vs 14.9 +/- 0.24; Day 8: 13.8 +/- 0.20 vs 15.4 +/- 0.2; Day 10: 14.8 +/- 0.24 vs 17.4 +/- 0.24; Day 12: 13.2 +/-0.25 vs 17.9 +/- 0.31; Day 16: 13.9 +/- 0.28 vs 16.5 +/- 0.31; Day 18: 13.0 +/- 0.22 vs 16.5 +/- 09.36, and Day 19: 15.0 +/- 0.23 vs 17.6 +/- 0.33 mum, respectively). The distribution of cell sizes was leptokurtotic throughout the estrous cycle and the first 10 d of pregnancy, but tended towards bimodality after Day 14 of pregnancy. The proportion of lutein cell cytoplasm occupied by vacuoles was lower in pregnant than in cyclic cows from the 12th day post estrus, but there was a marked (P<0.05) increase in vacuolation of cells from cows undergoing luteolysis. Stainable intercellular collagen was also less abundant in pregnant than cyclic cows from the 12th day post estrus. The higher rate of progesterone secretion of pregnant, compared with cyclic cows may be attributed to the greater numbers and greater contribution to luteal mass of large lutein cells in the corpus luteum of pregnancy.     

Distribution of peptide YY in the gastrointestinal tract of the rat, dog, and monkey

The objective of this study was to characterize the distribution and concentration of peptide YY (PYY) in the gastrointestinal tract of the rat, dog, and monkey. In the rat, the greatest concentration of PYY was detected in the ileum and colon. The concentrations of PYY in the ileum and colon were 72 +/- 49 and 768 +/- 180 ng/g tissue, respectively. In the dog, PYY was found primarily in extracts of the mucosal layer of the ileum and colon, with smaller amounts in the distal jejunum. The concentration of PYY in the mucosal layers of the canine distal jejunum was 113 +/- 25 ng/g tissue, proximal jejunum 302 +/- 56, mid jejunum 507 +/- 151, distal ileum 691 +/- 184, and colon 1706 +/- 774 ng/g tissue. In the monkey gastrointestinal tract, PYY was detected predominantly in mucosal extracts of the jejunum, ileum, and colon. The concentration of PYY in the mucosal layer extract of the jejunum was 92 +/- 23, ileum 615 +/- 127, and colon 1013 +/- 243 ng/g tissue.     

Influence of temperature on the calcium sensitivity of the myofilaments of skinned ventricular muscle from the rabbit

The steady-state myofilament Ca sensitivity was determined in skinned cardiac trabeculae from the rabbit right ventricle (diameter, 0.13-0.34 mm) at 36, 29, 22, 15, 8, and 1 degree C. Muscles were stimulated to 0.5 Hz and stretched to a length at which maximum twitch tension was generated. The preparation was then skinned with 1% vol/vol Triton X-100 in a relaxing medium (10 mM EGTA, pCa 9.0). Each preparation was exposed to a series of Ca-containing solutions (pCa 6.3-4.0) at two of the six temperatures studied (temperature was regulated to +/- 0.1 degree C). The pCa values (mean +/- SD, n = 6) corresponding to half maximal tension at 36, 29, 22, 15, 8, and 1 degree C were 5.47 +/- 0.07, 5.49 +/- 0.07, 5.34 +/- 0.05, 5.26 +/- 0.09, 4.93 +/- 0.06, and 4.73 +/- 0.04, respectively. Mean (+/- SD) maximum tension (Cmax) developed by the preparation as a percentage of that at 22 degrees C was 118 +/- 10, 108 +/- 5, 74 +/- 6, 57 +/- 7, and 29 +/- 5% at 36, 29, 15, 8, and 1 degree C, respectively. As cooling led to a shift of Ca sensitivity towards higher [Ca2+] and a reduction of Cmax, the Ca sensitivity curves over this range of temperatures do not cross over as has been described for canine Purkinje fibers (Fabiato 1985). Since tension is decreased by cooling at all levels of [Ca2+] it is unlikely that changes in myofilament Ca sensitivity play a role in the large hypothermic inotropy seen in rabbit ventricular muscle. The increase in sensitivity of the myofilaments to Ca on warming from 1 to 29 degrees C might be related to the increase in force seen on rewarming from a rapid cooling contracture in intact rabbit ventricular muscle.     

Distribution and subtype determination ofβ-receptors in the spinal cord of the adult rat

1. We determined the number of beta-receptors in the whole spinal cord of the adult rat and in the cervical, thoracal, and lumbal/sacral parts. 2. The undivided spinal cord contains 47 +/- 10 fmol/mg beta-receptors (KD = 2066 +/- 982 pmol/liter), and the cervical part of the spinal cord contains 53 +/- 8 fmol/mg protein (KD = 3224 +/- 1775 pmol/liter). The thoracal part shows 40 +/- 1 fmol/mg protein (KD = 3229 +/- 104 pmol/liter), and the lumbal/sacral spinal cord contains 48 +/- 8 fmol/mg protein (KD = 3610 +/- 1610 pmol/liter). 3. Competitive inhibition studies with l-practolol, dl-atenolol, and ICI 118,551 were performed and we calculated by a computer program in the whole spinal cord the following ratio of beta-receptor subtypes: 80 +/- 5% Beta 1-receptors and 20 +/- 5% beta 2-receptors. 4. The basal and (-)-isoproterenol- and NaF-stimulated activity of adenylate cyclase was highest in the cervical part of the spinal cord and equally distributed between the thoracal and the lumbal/sacral parts. 5. The whole synaptosomal protein of the cervical part of the spinal cord contained 132 +/- 20 fmol, the thoracal part 117 +/- 3 fmol, and the lumbal/sacral part 133 +/- 22 fmol.     

The cycle of the seminiferous epithelium in the Australian Swamp buffalo

The relative frequencies of stages and substages of the Swamp buffalo seminiferous epithelium were determined using a morphological classification. Duration of one cycle of the seminiferous epithelium was determined from radiolabelling studies using tritiated thymidine. Mean (+/-SD) duration of the cyle of the seminiferous epithelium of five Swamp buffalo was 8.74 +/- 0.18 d. Mean (+/-SEM) relative frequencies of stages and substages of the seminiferous epithelial cycle in ten bulls were Stage 1a, 7.27 +/- 0.72; Stage 1b, 8.11 +/- 0.85; Stage 1c, 8.54 +/- 1.13; Stage 2a, 5.9 +/- 0.79; Stage 2b, 7.49 +/- 0.78; Stage 3a, 9.05 +/- 0.66; Stage 3b, 9.69 +/- 1.11; Stage 4a, 5.04 +/- 0.44; Stage 4b, 4.8 +/- 0.69; Stage 5, 1.86 +/- 0.23; Stage 6, 8.81 +/- 0.84; Stage 7, 10.64 +/- 1.2; Stage 8a, 6.87 +/- 0.96; and Stage 8b, 5.93 +/- 0.72.     

In vivo effect of aluminium upon the physical properties of the erythrocyte membrane

Aluminium (Al (III)) is a metal with no biological function. Its organic accumulation can lead to toxic effects. To elucidate the in vivo effect of Al (III) upon the rheological properties of the erythrocyte membrane, male adult Wistar rats have been submitted to periodical injections of Al(OH)3 during three months. Significant decreases in haematocrit (34+/-0.37% versus 36+/-0.20%, p<0.0001) and blood haemoglobin concentration (10.7+/-0.15 g/dl versus 12.3+/-0.49 g/dl, p<0.005) have been found. Haemolysis curves shifted towards the left, indicating that erythrocytes became more resistant to hypotonic haemolysis. Significant increments in rigidity index (29.6+/-1.59 versus 9.2+/-0.40, p<0.0001), relative viscosity at native haematocrit (3.6+/-0.03 versus 3.5+/-0.03, p<0.04), and relative viscosity at standard haematocrit (4.5+/-0.06 versus 3.9+/-0.05, p<0.0001) have been observed. The decrease in the erythrocyte aggregate size (1.6+/-0.01 versus 1.7+/-0.01, p<0.002) and the aggregation rate (0.5+/-0.02 versus 0.6+/-0.03, p<0.002) indicated a significantly dropped aggregability process. In conclusion, Al (III) disorganised the erythrocyte membrane by altering its mechanical properties, suggesting a reduction of the middle life of circulating erythrocytes, which could play a major role in the anaemia of these animals.     

Ionic composition of endolymph and perilymph in the inner ear of the oyster toadfish, Opsanus tau

The concentrations of free Na+, K+, Ca(+, and Cl(-)in endolymph and perilymph from the inner ear of the oyster toadfish, Opsanus tau, were measured in vivo using double-barreled ion-selective electrodes. Perilymph concentrations were similar to those measured in other species, while endolymph concentrations were similar to those measured previously in elasmobranch fish, though significantly different from concentrations reported in mammals. Perilymph concentrations (mean +/- std. dev.) were as follows: Na+, 129 mmol l(-1) +/- 20; K+, 4.96 mmol l(-1) +/- 2.67; Ca2+, 1.83 mmol l(-1) +/- 0.27; and Cl(-), 171 mmol l(-1) +/- 20. Saccular endolymph concentrations were Na+, 166 mmol l(-1) +/- 22; K+, 51.4 mmol l(-1) +/- 16.7; Ca2+, 2.88 mmol l(-1) +/- 0.27; and Cl(-), 170 mmol l(-1) +/- 12; and semicircular canal (utricular vestibule) endolymph concentrations were Na+, 122 mmol l(-1) +/- 15; K+, 47.7 mmol l(-1) +/- 13.2; Ca2+, 1.78 mmol l(-1) +/- 0.48; Cl(-), 176 mmol l(-1) +/- 27. The relatively high concentrations of Ca2+ and Na+ in the endolymph may have significant implications for the physiological function of the mechanoelectrical transduction channels in the vestibular hair cells of fish compared to those of their mammalian counterparts.     

Ammonia-utilizing enzymes of adherent bacteria in the sheep's rumen

In experiments on 6 sheep the authors found the following enzyme activities in bacteria in the rumen fluid, bacteria adhering to the epithelium of the rumen wall and bacteria adhering to food particles in the rumen (given in nkat X g-1 bacterial dry weight): GDH (NADH): 725 +/- 165, 558 +/- 127, 661 +/- 153; GDH (NADPH): 558 +/- 338, 255 +/- 88, 565 +/- 139; GOAT (NADH): 46 +/- 23, 67 +/- 31, 66 +/- 14; GOGAT/NADPH: 58 +/- 27, 56 +/- 15, 65 +/- 29; GS: 153 +/- 65, 69 +/- 35, 71 +/- 32; ALT: 71 +/- 25, 43 +/- 20, 52 +/- 11; AST: 52 +/- 12, 33 +/- 16, 28 +/- 15. The results show that, except for GDH (NADPH), there were no significant differences between the given enzyme activities in the rumen fluid and in bacteria adhering to the rumen wall and to food. Adherent rumen bacteria have the same potential possibilities as the rumen fluid bacteria for the utilization of ammonia, particularly for the synthesis of glutamic acid, glutamine, alanine and aspartic acid, with the above enzymes as catalysts. By means of the GS/GOGAT system, adherent rumen bacteria can probably synthesize glutamic acid in the presence of a limited NH3 concentration in the rumen.     

Sexual maturity in rabbits defined by the physical and chemical characteristics of the semen

Semen was collected weekly from New Zealand white rabbits from the 1st positive mounting test to 43 weeks of age by means of an artificial vagina. The mean values of the results obtained in the 1st and 20th collection weeks were respectively: volume (ml) 0.61 +/- 0.30 and 0.70 +/- 0.19; pH 7.22 +/- 0.50 and 7.19 +/- 0.15; concentration (sperm/mm3 X 10(3)) 750 +/- 207 and 381 +/- 90; fructose (mg/100 ml) 117 +/- 58 and 203 +/- 121; citric acid (mg/100 ml) 256 +/- 90 and 200 +/- 97; sodium ions (mEq/l) 133 +/- 31 and 163 +/- 46; potassium ions (mEq/l) 40 +/- 21 and 29 +/- 14. On the basis of these results, New Zealand white rabbits reach sexual maturity by 6 months of age.     

Oxygen binding and acid base status of the blood from the freshwater turtle, Phrynops hilarii

Oxygenation studies with the whole blood of Phrynops hilarii show a P50 of 38 torr at extracellular pH (pHe) of 7.4 which corresponds to an intracellular pH (pHi) of 7.05 at 25 degrees C. The blood CO2 Bohr effect was -0.56 when related to pHi. pHi is related to pHe by the following equation: pHi = 0.75.pHe + 1.54 (r = 0.99); pHi = 0.72. pHe + 1.72 (r = 0.96) at 10 and 25 degrees C respectively. Blood pHe, for 25 degrees C, was 7.519 +/- 0.254 (n = 6). Blood gas partial pressures were: pCO2 = 25.8 +/- 3.8 torr (n = 6); pO2 = 61.7 +/- 21.2 torr (n = 6). The major red cell phosphates, in mmole/l erythrocytes, n = 6, were: ATP (3.66 +/- 0.86); GTP (0.53 +/- 0.28); 2.3-DPG (0.32 +/- 0.12) and inorganic phosphates (2.00 +/- 0.35). The plasma inorganic ion composition, n = 6, was, in mEq/l: K+ (3.04 +/- 0.40); Na+ (148.4 +/- 12.6); Ca2+ (4.75 +/- 1.32); Cl- (106.6 +/- 5.0). Additional blood parameters of interest (n = 6) were: lactate (2.07 +/- 1.72 mM in plasma); erythrocytes/mm3 (416 X 10(3) +/- 4.6 X 10(3)); leucocytes/mm3 (44636 +/- 2618); haematocrit (%) (14.5 +/- 3.6); haemoglobin, g/dl (3.2 +/- 0.5); plasma protein g/dl (4.4 +/- 0.4); osmolarity (293 +/- 10 mOsm/l). The non-bicarbonate buffer value was -22.6 mmol/kg H2O/pH. For a constant CO2 content, delta pHe/delta t = 0.0141 +/- 0.002 (n = 18) and delta pHi/delta t = 0.0157 +/- 0.003 (n = 18).     

Microcinematographic study of the lengthening of the cell cycle after x-ray and fast neutron irradiation

The median cycle duration of unirradiated EMT6 cells is equal to 9.68 +/- 0.20 h. It reaches 10.77 +/- 0.42 h, 12.95 +/- 0.62 h, 14.95 +/- 1.10 h, 16.15 +/- 1.87 h and 20.25 +/- 2.25 h after 250 kV X-rays doses of 1 Gy, 2 Gy, 4 Gy, 6 Gy and 8 Gy respectively and 11.23 +/- 1.03 h, 13.40 +/- 0.53 h and 15.13 +/- 1.15 h after p(65) + Be neutron doses of 0.75 Gy, 1.5 Gy and 2.5 Gy respectively. The corresponding mitotic delay (Tc irradiated - Tc controls) may be evaluated equal to congruent to 1.15 h per Gy for X-rays and to congruent to 2.30 h per Gy for neutrons.     

Etiology of purulent septic diseases and the antibiotic resistance of the isolated causative agents

Among the causative agents of purulent septic diseases in the surgical hospital, 25 microbial species were isolated; of these, the prevailing species were Staphylococcus aureus (19.86 +/- 1.07%), Escherichia coli (16.5 +/- 0.99%) and Pseudomonas aeruginosa (10.06 +/- 0.8%). From environmental objects in the hospital 14 microbial species were isolated, among them bacteria of the genus Enterobacter (27 +/- 1.7%), E. coli (19.07 +/- 1.48%), S. aureus (14.7 +/- 1.31%), Klebsiella pneumoniae (13.73 +/- 1.31%), P. aeruginosa (7.33 +/- 0.98%). During 3 years of observation the isolation rate of K. pneumoniae from different environmental objects was found to increase threefold to 24.7 +/- 2.7%. The results of the study of the microbial picture in surgical hospitals, as well as the antibiotic resistance of circulating causative agents, should be borne in mind while taking epidemic control measures.     

Pregnancy impairs the counterregulatory response to insulin-induced hypoglycemia in the dog

The impact of pregnancy on the counterregulatory response to insulin-induced hypoglycemia was examined in six nonpregnant (NP) and six pregnant (P; 3rd trimester) conscious dogs by tracer and arteriovenous difference techniques. After basal sampling, insulin was infused intraportally at 30 pmol.kg(-1).min(-1) for 180 min. Insulin rose from 70 +/- 15 to 1,586 +/- 221 pmol/l and 27 +/- 4 to 1,247 +/- 61 pmol/l in the 3rd h in NP and P, respectively. Arterial glucose fell from 5.9 +/- 0.2 to 2.3 +/- 0.2 mmol/l in P. Glucose was infused in NP to equate the rate of fall of glucose and the steady-state concentrations in the groups (5.9 +/- 0.2 to 2.3 +/- 0.1 mmol/l in NP). Glucagon was 32 +/- 6, 69 +/- 11, and 48 +/- 10 ng/l (basal and 1st and 3rd h) in NP, but the response was attenuated in P (34 +/- 5, 46 +/- 6, 41 +/- 9 ng/l). Cortisol and epinephrine rose similarly in both groups, but norepinephrine rose more in NP (Delta3.01 +/- 0.46 and Delta1.31 +/- 0.13 nmol/l, P < 0.05). Net hepatic glucose output (NHGO; micromol.kg(-1).min(-1)) increased from 10.6 +/- 1.8 to 21.2 +/- 3.3 in NP (3rd h) but did not increase in P (15.1 +/- 1.5 to 15.3 +/- 2.8 micromol.kg(-1).min(-1), P < 0.05 between groups). The glycogenolytic contribution to NHGO in NP increased from 5.8 +/- 0.7 to 10.4 +/- 2.5 micromol.kg(-1).min(-1) by 90 min but steadily declined in P. The increase in glycerol levels and the gluconeogenic contribution to NHGO were 50% less in P than in NP, but ketogenesis did not differ. The glucagon and norepinephrine responses to insulin-induced hypoglycemia are blunted in late pregnancy in the dog, impacting on the magnitude of the metabolic responses to the fall in glucose.     

Adenylate cyclase activity of the corpus luteum during the oestrous cycle of the pig

Basal adenylate cyclase values for corpora lutea (CL) removed from cyclic gilts on Days 3, 8, 13 and 18 were 178 +/- 61, 450 +/- 46, 220 +/- 25 and 208 +/- 18 pmol cAMP formed/min/mg protein, respectively. Basal activity was significantly elevated on Day 8 (P less than 0.001). LH-stimulatable adenylate cyclase values for CL from Days 3, 8, 13 and 18 were 242 +/- 83, 598 +/- 84, 261 +/- 27 and 205 +/- 17 pmol cAMP formed/min/mg protein respectively. Serum progesterone concentrations of 12 gilts bled every 2 days through one complete oestrous cycle ranged from 1.1 to 26.9 ng/ml with highest values between Days 8 and 12. The decline in serum progesterone concentrations was coincident with the decrease in basal adenylate cyclase activity. There was no LH-stimulatable adenylate cyclase activity present in the CL at the specific times of the oestrous cycle examined. We conclude that progesterone secretion by the pig CL is apparently dependent on basal activity of adenylate cyclase.     

Gangliosides in the blood plasma: levels of ganglio-series gangliosides in the plasma after administration of brain gangliosides

The temporal change in the levels of the gangliotetraose-series gangliosides, i.e., GMla, GDla, GD1b, GT1b, in the blood plasma after intramuscular administration of bovine brain gangliosides (5 mg/kg) to beagle dogs (11.3-12.2 kg) was determined with high sensitivity by a recently developed thin-layer chromatography/enzyme-immunostaining method (Hirabayashi, Y., Koketsu, K., Higashi, H., Suzuki, Y., Matsumoto, M., Sugimoto, M. and Ogawa, T. (1986) Biochim. Biophys. Acta 876, 178-182). The amounts of GMla, GDla, GD1b, GT1b and their combined total in the plasma of beagle dogs before administration of gangliosides were 21 +/- 1, 36 +/- 7, 15 +/- 2, 16 +/- 2 and 88 +/- 6 pmol/ml of blood plasma, respectively. Trapezoidal calculation showed that the times of the maximum levels of GMla, GDla, GDlb, GTlb and the total of the their levels in the plasma were 8.0 +/- 1.2, 8.7 +/- 0.7, 6.3 +/- 2.0, 17.0 +/- 7.0 and 8.7 +/- 0.7 h after the administration of gangliosides, and their maximum concentrations were 517 +/- 37, 654 +/- 53, 160 +/- 5, 184 +/- 20 and 1383 +/- 74 pmol/ml, respectively. The maximum level of each ganglioside decreased gradually, reaching the normal level after 10 days. The half-maximum level of each ganglioside occurred 2-3 days after the administration. Asialo GM1 (GA1) was not detected plasma at any of the test times.     

Change in the electrophysiological parameters of rat oocytes maturing in vivo

The membrane potential (MP) and input membrane resistance (R) were measured in the immature (1) and mature ovulated (2) rat eggs. The population 1 is homogeneous enough: in 78.3% of all oocytes MP equaled --18 +/- 0.3 mV and R = 3 +/- 0.6 mO; 21.7% of cells had MP = --2 +/- 0.9 MV and R = 3.5 +/- 0.6 mO. The population 2 was divided by the indices under study into 4 groups. The respective values of MP and R in each of 4 groupd 5.5 +/- 0.5 mO, c) --15 +/- 0.6 mV and 7 +/- 1.0 mO, d) --3 +/- 0.4 mV and 9 +/- 0.5 mO. A suggestion is put forward that MP and R of the oocytes change with respect to the maturation stage.     

Mechanism of 3-deazaguanine transport in the rat heart

The aim of this study was to determine the mechanism of transport of 3-deazaguanine in the rat heart. We used single-pass, paired-tracer dilution method on isolated and retrogradely perfused rat hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 3-deazaguanine were determined under control conditions and under influence of possible modifiers. Both Umax and Utot were significantly reduced in the presence of unlabeled 3-deazaguanine (from 19.57 +/- 2.02% to 8.14 +/- 1.19% and from 16.49 +/- 3.65% to 4.70 +/- 1.96%, n=6, respectively). The presence of pyrimidine nucleoside thymidine caused the reduction of both Umax and Utot (from 20.03 +/- 3.76% to 13.58 +/- 3.16% and from 16.43 +/- 3.58% to 11.94 +/- 3.13%, n=6, respectively). Also, we tested the effect of the absence of sodium ions in perfusion solution (both Umax and Utot, significantly reduced from 17.95 +/- 2.73% to 16.67 +/- 2.16% and from 16.68 +/- 2.97% to 14.81 +/- 3.04%, n=6, respectively) and the effect of dinitrophenol (both Umax and Utot significantly reduced from 19.09 +/- 3.68% to 10.58 +/- 3.14% and from 16.86 +/- 3.84% to 7.10 +/- 3.11%, n=6, respectively). The results of self- and cross-inhibition studies show that the transport of 3-deazaguanine is saturable, energy- and sodium-dependent and that 3-deazaguanine uses endogenous transport systems for thymidine and adenosine for its own transport.     

Catecholamine production along the nephron.

The present work proposes an extra neural site of catecholamine production along the nephron. LLC-PK(1), MDCK, and mIMCD-3 (proximal and distal tubules and inner medullary collecting duct, respectively) presented the following amine concentrations in the cell homogenates: Norepinephrine = 275+/-34, 56+/-16 and 255+/-21; Epinephrine = 161+/-20, 83+/-17 and 53+/-7; and Dopamine = 63+/-15, 39+/-6 and 36+/-7 pg/mg cell protein (Means +/- SEM), respectively. The culture medium showed Norepinephrine = 168+/-25, 22+/-3 and 135+/-8; Epinephrine = 32+/-6, 152+/-17 and 39+/-5; and Dopamine = 27+/-9, 241+/-34 and 26+/-5 pg/mg cell protein, respectively. The synthesis enzymes as tyrosine hydroxylase, dopa decarboxylase and dopamine beta-hydroxylase were detected by Western blotting. Biopterin, the enzymatic cofactor of tyrosine hydroxylase, was quantified in the intracellular and medium of mIMCD-3 cells (17+/-4 and 24+/-3 nmol/mg cell protein, respectively) and in the medium of MDCK cells (19+/-4 nmol/mg cell protein). The data confirmed that the proximal tubule is an important source of dopa decarboxilase and Dopamine and epithelial cell along the nephron express the biochemical pathway for catecholamine production.     

Changes in the rate of axonal flow of proteins through the branches of motor and sensory neurocytes during the period of intense growth of the sciatic nerve in rats

14C-glycin was microinjected into the ventral horns of the spinal cord or spinal ganglions. The rate of fast and slow axoplasmic transport of proteins in the axons of motor and sensory neurons was studied by liquid scintillation. Motor fibers of the sciatic nerve manifested a marked decrease (P less than 0.05) in the rate of slow axoplasmatic transport of the labeled protein from 5.25 +/- 0,31 in 2-week-old rats to 3.45 +/- +/- 0.23 mm/day in 4-week-old animals and a significant increase in the rate of fast axoplasmic transport (P less than 0.05) from 99 +/- 13.2 (2-week-old rats) up to 198 +/- 18.9 mm/day (in 4-week-old rats). The two-week-old rats had higher rates (4.5 +/- 0.3 mm/day) of slow axoplasmic transport of the labeled protein in the central and peripheral axons of sensory neurocytes and lower rates of fast axoplasmic transport (126 +/- 14.7 mm/day) as compared with 4-week-old animals (3.75--4.1 +/- 0.25 -- slow transport; 144 +/- 23.34 mm/day -- fast transport). However, the differences described are not significant.