Galanin-, neuropeptide Y- and enkephalin-like immunoreactivities in catecholamine-storing paraganglia of the fetal guinea pig and newborn pig

Summary The occurrence and distribution of several neuropeptides and transmitter enzymes have been investigated by means of indirect immunofluorescence histochemistry in preaortal and carotid body-like paraganglia of the fetal guinea pig and the newborn pig. Preaortal paraganglia from the celiac and inferior mesenteric ganglion regions in fetal guinea pigs showed cell bodies immunoreactive (IR) for tyrosine hydroxylase (TH), dopamine -hydroxylase (DBH), neuropeptide Y (NPY), galanin (GAL) and metenkephalin (ENK). Almost all cells were IR for TH and DBH, whereas NPY-like immunoreactivity (-LI), GAL-LI and ENK-LI occurred less frequently. Direct double-labeling revealed the coexistence of NPY/GAL, NPY/ENK and GAL/ENK in paraganglion cells from the celiac and inferior mesenteric region. Nerve fibers and terminals were IR for ENK; fibers IR for calcitonin-gene-related peptide (CGRP) were present in the inferior mesenteric ganglion region. Preaortal paraganglia cells from the newborn pig showed TH-LI, DBH-LI, GAL-LI and ENK-LI, the distribution pattern being similar to that seen in the guinea pig; however, NPY-LI was absent. Carotid-body-like paraganglia from the newborn pig showed cell bodies IR to TH, GAL and ENK. Few cells were seen with DBH-LI. A rich supply of nerve fibers with CGRP-LI was present; some fibers exhibited ENK-LI and CCK-LI. In the adjacent superior cervical ganglion, ganglion cell bodies showed immunoreactivity to TH, DBH and NPY. A small number of cells were positive for GAL, CGRP and vasoactive intestinal polypeptide (VIP). Physiological activation of the paraganglia, leading to release or increase in catecholamines, may also change the content of the neuropeptides present in the paraganglia.     

Catecholamine-synthesizing enzymes and neuropeptides in rat heart epicardial ganglia; an immunohistochemical study

Summary The subepicardial atrial ganglia of rat hearts were examined using immunohistochemical techniques and antibodies against the catecholamine-synthetic enzymes tyrosine hydroxylase (TH) and dopamine--hydroxylase (DBH), and the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and met-5-enkephalin (ENK). Some of the ganglion cells present in the ganglia exhibited DBH-like immunoreactivity (LI) and NPY-LI, whilst these cells nerver exhibited TH-, VIP-, CGRP-, SP- or ENK-LI. Groups of small cells exhibiting an intense TH-LI, corresponding to cells referred to as catecholamine-containing cells and sometimes small intensely fluorescent cells in the literature, were observed in the ganglia. A subpopulation of these cells exhibited immunoreactivity to one of the neuropeptides tested, namely SP. Only a few of the cells showing TH-LI displayed DBH-LI. Nerve fibres showing SP-, CGRP-, DBH- and TH-LI were present in the ganglia; some of these fibres being closely associated with the ganglion cells or with the cells showing TH-LI. The observations provide new information on the catecholaminesynthetic enzyme/neuropeptide expression of the ganglion and catecholamine-containing cells and of the associated nerve fibres of rat heart subepicardial ganglia.     

Innervation of the large arteries and heart of the toad (Bufo marinus) by adrenergic and peptide-containing neurons

Summary The innervation of the major arteries and heart of the toad (Bufo marinus) was examined by use of glyoxylic acid-induced catecholamine fluorescence and peptide immunohistochemistry. All arteries possessed a moderate to dense plexus of adrenergic axons, which also showed neuropeptide Y-like immunoreactivity (NPY-LI). Some adrenergic axons in the intracardiac vagal trunks showed NPY-LI, but the varicose adrenergic axons innervating the cardiac muscle of the atria and ventricle, and the coronary blood vessels did not display NPY-LI. About half of the nerve cell bodies in the anterior sympathetic chain ganglia with dopamine--hydroxylase-LI (DBH-LI) also contained NPY-LI. The nerve cell bodies with DBH-LI alone were generally larger (median diameter 30 m) than those with both DBH-LI and NPY-LI (median diameter 20 m). Some cell bodies showing DBH-LI alone were surrounded by boutons with NPY-LI but not DBH-LI. Axons that displayed simultaneously both substance P-LI (SP-LI) and calcitonin gene-related peptide-LI (CGRP-LI) also formed a plexus around all arteries studied, being particularly dense around the mesenteric and pulmonary arteries. These axons are most likely sensory since SP-LI was reduced by capsaicin treatment, and nerve cell bodies with both SP-LI and CGRP-LI were found in dorsal root ganglia and the vagal ganglion. A dense plexus of axons showing somatostatin-LI was located around the pulmonary artery and its main intrapulmonary branches. A few nerves with vasoactive intestinal polypeptide-LI were found around the dorsal aorta and pulmonary artery. No perivascular nerves with enkephalin-LI were observed. Reversed-phase, high-pressure liquid chromatography of acid extracts of the large arteries showed that the major peaks of NPY-LI and SP-LI coeluted with porcine NPY (1–36) and synthetic SP (1–11), respectively. Thus, the location and structure of these peptides in perivascular nerves has been highly conserved during vertebrate evolution.     

Stop-flow: A new technique for measuring axonal transport,and its application to the transport of dopamine-β-hydroxylase

An apparatus was devised which utilizes local cooling to reversibly interrupt the axonal transport of dopamine-β-hydroxylase (DBH) in rabbit sciatic nerves in vitro. Lowering the temperature of a short region of nerve to between 1 and 3°C, while keeping the remainder at 37°C, caused DBH activity to accumulate in and proximal to the cooled region. This accumulation was evident after 0.5 hr of cooling and increased in a nearly linear fashion with time for about 3 hr. The cooling-induced interruption in transport was rapidly reversed when nerves were rewarmed to 37°C. Upon rewarming after local cooling for 1.5 hr, a peak of accumulated DBH activity migrated toward the distal end of the nerve at a velocity of 300 ± 17 mm/day. This velocity was maintained for as long as the peak could be followed and was four times greater than the average velocity estimated from the rate of accumulation of DBH activity above a ligature at the distal end of these same nerves. It is concluded that ligation experiments grossly underestimate the true velocity of axonal transport of DBH and that the present technique offers great advantages in permitting direct study of the migration of separate axonal compartments of transported materials.     

Stop-flow: a new technique for measuring axonal transport, and its application to the transport of dopamine-beta-hydroxylase.

An apparatus was devised which utilizes local cooling to reversibly interrupt the axonal transport of dopamine-beta-hydroxylase (DBH) in rabbit sciatic nerves in vitro. Lowering the temperature of a short region of nerve to between 1 and 3 degrees C, while keeping the remainder at 37 degrees C, caused DBH activity to accumulate in and proximal to the cooled region. This accumulation was evident after 0.5 hr of cooling and increased in a nearly linear fashion with time for about 3 hr. The cooling-induced interruption in transport was rapidly reversed when nerves were rewarmed to 37 degrees C. Upon rewarming after local cooling for 1.5 hr, a peak of accumulated DBH activity migrated toward the distal end of the nerve at a velocity of 300 +/- 17 mm/day. This velocity was maintained for as long as the peak could be followed and was four times greater than the average velocity estimated from the rate of accumulation of DBH activity above a ligature at the distal end of these same nerves. It is concluded that ligation experiments grossly underestimate the true velocity of axonal transport of DBH and that the present technique offers great advantages in permitting direct study of the migration of separate axonal compartments of transported materials.     

Occurrence and distribution of neuropeptide-Y-immunoreactive nerves in the respiratory tract and middle ear

Summary Nerve fibres displaying neuropeptide-Y (NPY) immunoreactivity are abundantly distributed in the respiratory tract of cats, guinea-pigs, rats and mice. Fine beaded NPY fibres were seen in whole-mount spreads of the middle-ear mucosa. In the nasal mucosa and in the wall of the Eustachian tube NPY fibres were numerous around arteries and arterioles but sparse in the vicinity of veins; single fibres were found close to the acini of seromucous glands. In the tracheobronchial wall NPY fibres occurred in the proximity of blood vessels, in the subepithelial layer and in the smooth muscle. Surgical and chemical (6-hydroxydopamine treatment) sympathectomy resulted in disappearance of adrenergic and NPY-containing nerve fibres in the nasal mucosa. Sequential staining with antibodies against dopamine--hydroxylase (DBH) and NPY revealed that DBH and NPY occur in the same perivascular nerve fibres in the nasal mucosa. The distribution of NPY fibres in the respiratory tract suggests multiple functions of NPY, such as regulation of local blood flow, glandular secretion and smooth muscle activity.     

Detection of neuropeptide Y-like immunoreactivity and messenger RNA in rat platelets: the effects of vinblastine, reserpine, and dexamethasone on NPY expression in blood cells.

Rat plasma contains high basal levels (220 pmol/liter) of neuropeptide Y (NPY)-like immunoreactivity (LI) compared to pig (30 pmol/liter) and man (25 pmol/liter). The platelet-enriched fraction (PEF), obtained from rat blood contained 10,061 pmol/g NPY-LI. However, in human and pig blood, the PEF contained very low levels of NPY-LI. Gradient centrifugation of rat blood showed the highest concentration of NPY-LI (10.8 +/- 0.4 pmol/g) in the platelet fraction. The mononuclear cell fraction contained 1.64 +/- 0.16 pmol/g, whereas only 0.56 +/- 0.06 pmol/g of NPY-LI was found in the red blood cell/polymorphonuclear cell fraction. Characterization of NPY-LI in rat plasma and platelets by high-pressure liquid chromatography showed one predominating peak which coeluted with synthetic NPY (1-36) as well as three minor peaks, one of which coeluted with oxidized NPY. Analysis of NPY messenger RNA (mRNA) in bone marrow of the rat revealed a 0.79-kb-long NPY mRNA. This size is intermediate to the 0.82-kb NPY mRNA in brain and the 0.76-kb NPY mRNA in spleen. The highest level of NPY mRNA in rat blood was found in the mononuclear cell fraction but NPY mRNA was also detected in the platelet fraction. No NPY mRNA was detected in bone marrow or blood from pig and rabbit or from human blood or bone marrow. Forty-eight hours after treatment of rats with vinblastine the content of NPY mRNA and NPY-LI in rat blood was decreased, while the level of NPY-LI in bone marrow was markedly enhanced. Reserpine treatment caused an increase in NPY mRNA content in bone marrow and spleen. After administration of dexamethasone the level of NPY mRNA increased in both spleen and peripheral blood cells with increased NPY-LI content in the spleen. It is concluded that in addition to megakaryocytes in spleen and bone marrow, platelets and possibly also lymphocytes/monocytes in peripheral blood of the rat contain NPY mRNA and peptide. The expression of NPY mRNA in bone marrow, spleen, and blood is influenced by vinblastine, reserpine, and dexamethasone.     

Axonal transport of synaptic vesicle proteins in the rat optic nerve

The optic nerve, as a part of the central nervous system (CNS), has been used to study axonal transport for decades. The present study has concentrated on the axonal transport of synaptic vesicle proteins in the optic nerve, using the “stop-flow/nerve crush” method. After blocking fast axonal transport, distinct accumulations of synaptic vesicle proteins developed during the first hour after crush-operation and marked increases were observed up to 8 h postoperative. Semiquantitative analysis, using cytofluorimetric scanning (CFS) of immunoincubated sections, revealed that the ratio between distal accumulations (organelles in retrograde transport) and proximal accumulations (organelles in anterograde transport) was much higher (up to 80–90%) for the transmembrane proteins than that for surface adsorbed proteins (only 10–20%). The pattern of axonal transport in the optic nerve was comparable to that in the sciatic nerve. However, clathrin and Rab3a immunoreactivities were accumulated in much lower amounts than that in the sciatic nerve. Most synaptic vesicle proteins were colocalized in the axons proximal to the crush. A differential distribution of synaptobrevin I and II, however, was observed in the optic nerve axons; synaptobrevin I was present in large-sized axons, while synaptobrevin II immunoreactivity was present in most axons, including the large ones. The two isoforms were, thus, partially colocalized. The results demonstrate that (1) cytofluorimetric scanning techniques could be successfully used to study axonal transport not only in peripheral nerves, but also in the CNS; (2) synaptic vesicles are transported with fast axonal transport in this nerve; and (3) some differences were noted compared with the sciatic nerve, especially for Rab3a and clathrin. © 1997 John Wiley & Sons, Inc. J Neurobiol 32: 237–250, 1997.     

Studies on colocalization of neuropeptide Y,vasoactive intestinal polypeptide,catecholamine-synthesizing enzymes and acetylcholinesterase in the larynx of the rat

Summary In the present immunohistochemical study, the distribution of nerve fibers containing neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in the larynx was examined and compared with that of fibers containing tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (BDH), and with that of acetylcholinesterase (AChE)-positive nerve fibers, in intact and vagotomized rats and in rats subjected to removal of the superior cervical ganglion (SCG). Fibers showing TH/DBH-like immunoreactivity (LI) were only found in the walls of arteries and arterioles, whereas AChE-positive nerve fibers were located close to the acini and ducts of the glands, in blood vessel walls, in the perichondrium and in the lamina propria. NPY-LI and VIP-LI coexisted in local AChE-positive ganglionic cells and in a subpopulation of the AChE-positive fibers, NPY-LI also being present in some periarterial fibers showing TH/DBH-LI. Unilateral removal of the SCG eliminated the TH/DBH-innervation in the upper but not the lower parts of the larynx ipsilaterally, whereas the NPY-innervation of the arteries in the upper parts only partly disappeared and the NPY-innervation of the other structures remained unchanged. The distribution of VIP-innervation was unchanged after vagotomy and removal of the SCG. The results suggest that VIP is present in the postganglionic parasympathetic innervation, whereas NPY is present in both the postganglionic parasympathetic and sympathetic innervation of the rat larynx.     

Neuropeptide Y: Intrapancreatic neuronal localization and effects on insulin secretion in the mouse

Summary The intrapancreatic localization and the effects on basal and stimulated insulin secretion of neuropeptide Y (NPY) were investigated in the mouse. Immunocyto-chemistry showed NPY to be confined to intrapancreatic nerve fibers mainly associated with blood vessels. Fine varicose NPY fibers were also detected in the exocrine parenchyma and occasionally also within the islets. Double-staining experiments with the use of antisera for both NPY and tyrosine hydroxylase (TH) indicated that most of the NPY fibers were nonadrenergic in nature. Only a population of the NPY fibers occurring around blood vessels showed TH immunoreactivity. Under in vivo conditions, NPY was found to elevate plasma insulin levels slightly when injected intravenously at the high dose level of 8.5 nmol/kg. At lower dose levels, NPY did not affect basal plasma insulin levels, but instead inhibited glucose-induced insulin secretion. Thus, the glucose-induced increment in plasma insulin levels, which was 120±7U/ml in controls, was reduced to 87 ±5 U/ml by NPY at 4.25 nmol/kg (p<0.01) and to 98±6U/ml by NPY at 1.06 nmol/kg (p<0.05). In contrast, the insulin secretory response to the cholinergic agonist carbachol was not affected by NPY. We conclude that NPY nerve fibers occur in the mouse pancreas and that most of these NPY nerve fibers are nonadrenergic. Furthermore, in the mouse, NPY enhances basal plasma insulin levels at high dose levels and inhibits glucose-induced, but not cholinergically induced insulin secretion at lower dose levels under in vivo conditions.     

Storage and fast transport of noradrenaline, dopamine beta-hydroxylase and neuropeptide Y in dog sciatic nerve axons.

The axonal transport and subcellular distribution of noradrenaline (NA), dopamine beta-hydroxylase (DBH) and neuropeptide Y (NPY) were determined in dog sciatic nerve using an accumulation technique. The results were compared with those obtained by application of the same procedures and methods on the splenic nerve in the same animal species. Evidence was found for the coexistence of NA and NPY in large dense-cored vesicles in dog sciatic nerve axons. After differential centrifugation and isopyenic sucrose density gradient centrifugation of 24 h ligated sciatic nerve pieces NA and NPY equilibrated around 1M sucrose. The DBH activity was dispersed broadly on the gradient. Subsequently, the accumulation of NA, DBH and NPY was studied in proximal and sital segments of 8, 12 and 24 h dog ligated sciatic nerve and inferences were made concerning the axonal transport of these compounds. NA, DBH and NPY displayed a divergent accumulation proximal to the ligation. After 12 h of ligation a transport rate was calculated of 4.8 +/- 1.8 mm/h for NA, of 5.9 +/- 1.5 mm/h for DBH and of 4.9 +/- 2.0 mm/h for NPY. With a correction for the stationary fractions, a similar fast transport rate of approximately 10 to 12 mm/h was proposed for NA, DBH and NPY. The occurrence was shown of a limited retrograde transport of DBH and possibly NPY, but not of NA.     

Ganglion cells immunoreactive for catecholamine-synthesizing enzymes,neuropeptide Y and vasoactive intestinal polypeptide in the rat adrenal gland

Immunohistochemistry has been used to demonstrate tyrosine hydroxylase (TH), dopamine--hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) immunoreactivities, and acetylcholinesterase (AChE) activity was demonstrated in rat adrenal glands. The TH, DBH, NPY and VIP immunoreactivities and AChE activity were observed in both the large ganglion cells and the small chromaffin cells whereas PNMT immunoreactivity was found only in chromaffin cells, and not in ganglion cells. Most intraadrenal ganglion cells showed NPY immunoreactivity and a few were VIP immunoreactive. Numerous NPY-immunoreactive ganglion cells were also immunoreactive for TH and DBH; these cells were localized as single cells or groups of several cells in the adrenal cortex and medulla. Use of serial sections, or double and triple staining techniques, showed that all TH- and DBH-immunoreactive ganglion cells also showed NPY immunoreactivity, whereas some NPY-immunoreactive ganglion cells were TH and DBH immunonegative. NPY-immunoreactive ganglion cells showed no VIP immunoreactivity. AChE activity was seen in VIP-immunopositive and VIP-immunonegative ganglion cells. These results suggest that ganglion cells containing noradrenaline and NPY, or NPY only, or VIP and acetylcholine occur in the rat adrenal gland; they may project within the adrenal gland or to other target organs. TH, DBH, NPY, and VIP were colocalized in numerous immunoreactive nerve fibres, which were distributed in the superficial adrenal cortex, while TH-, DBH- and NPY-immunoreactive ganglion cells and nerve fibres were different from VIP-immunoreactive ganglion cells and nerve fibres in the medulla. This suggests that the immunoreactive nerve fibres in the superficial cortex may be mainly extrinsic in origin and may be different from those in the medulla.     

Norepinephrine,dopamine, and 5-HT release from perfused hypothalamus of the rat during feeding induced by neuropeptide Y

In the unrestrained rat, the hyperphagic-like ingestion of food evoked by the sustained elevation of neuropeptide-Y (NPY) in the hypothalamus was correlated with the release and turnover of monoaminergic transmitters in this structure. A single guide tube was implanted stereotaxically in the perifornical region of the hypothalamus for localized push-pull perfusion of an artificial CSF vehicle or NPY_1–36 in a concentration of 10, 50, or 100 ng/1.0 l. After the rat was fully satiated, a site reactive to NPY was perfused repeatedly at a rate of 20 l/min for 6.0 min with an interval of 6.0–12 min elapsing between each perfusion. Samples of perfusate were analyzed by HPLC with coulometric detection for DA, HVA, DOPAC, NE, MHPG, 5-HT, and 5-HIAA. Although control perfusions were without effect on feeding or monoamine activity, NPY evoked mean cumulative intakes of food of 14±2.4, 25.6±3.0 and 26.5±3.2 g in response to 10, 50, or 100 ng/l concentrations of NPY, respectively, over the 4.0–5.0 hr test interval. HPLC analyses showed that during feeding the release of both NE and DA was enhanced significantly. The turnover of both catecholamines likewise increased significantly as reflected by the elevated levels of MHPG, DOPAC and HVA. However, neither the basal efflux of 5-HT nor its turnover, as reflected by the output of 5-HIAA, was affected during feeding induced by NPY perfused in the hypothalamus. These results suggest that a sustained elevation of NPY in the hypothalamus causes a perturbation in the basal activity of NE and DA which are both implicated in the neuronal mechanism regulating normal eating behavior. Thus, these catecholamine neurotransmitters are envisaged to comprise an intermediary step in the functional role played by NPY in the hypothalamus in integrating the control of energy metabolism and caloric intake.     

Partial Isolation of Two Classes of Dopamine β-Hydroxylase-Containing Particles Undergoing Rapid Axonal Transport in Rat Sciatic Nerve

The rapid bidirectional transport of dopamine beta-hydroxylase (DBH) in adrenergic axons provides a means of analyzing the life cycle of adrenergic storage vesicles. We compared the physical characteristics of DBH-containing particles traveling to or returning from the terminal varicosities of ligated rat sciatic nerves. Density gradient centrifugation and Sephacryl S1000 gel-permeation chromatography were used to fractionate extracts from nerve segments proximal or distal to the ligatures. A series of experiments indicated the existence of at least two populations of rapidly transported DBH-containing particles, a "light" 85-nm particle and a larger "dense" 120-nm particle. The 85-nm particles were prevalent in unligated nerve, but accounted for only one-third of the total anterogradely transported DBH activity accumulated after 18 h. The 120-nm particles were barely detectable in the unligated nerve, but they accumulated at twice the rate of the 85-nm particles and accounted for the rest of the anterogradely transported particulate DBH activity. These two populations of particles were readily isolated from proximal nerve extracts by sucrose density gradient centrifugation. Similar-appearing dense and light peaks of particulate DBH activity were obtained from distal nerve extracts. Much of the retrogradely transported DBH of the extracts, however, was associated with large particles (greater than 300 nm) not resolved by Sephacryl S1000. Retrogradely transported exogenous NGF was found only in the dense sucrose gradient peak. We propose that the 85-nm DBH-containing particles correspond to "large dense-cored vesicles," and that the 120-nm particles are derived from the dense tubules visualized in adrenergic nerves by the chromaffin reaction.     

Distribution of dopamine-beta-hydroxylase-like immunoreactivity in the rat pineal organ

The aim of the present investigation was to study the distribution in the rat pineal gland of dopamine-beta-hydroxylase (DBH) which is essential for the formation of the melatonin synthesis-regulating substance noradrenaline (NA). In 5- and 8-month-old male Sprague-Dawley rats DBH-like immunoreactivity (DBH-LI) was studied using polyclonal antibodies against DBH and the indirect immunofluorescent technique. DBH-LI was mainly located in pineal nerve fibres coming from the superior cervical ganglia. The intensity of the staining reaction was considerably lower than in non-pineal noradrenergic nerve fibres and the impression was gained by comparison of DBH-LI specimens with glyoxylic acid-treated sections that only approximately one third of the NA-containing intrapineal nerve fibres exhibited DBH-LI. There were no detectable differences in DBH-LI with regard to time of day and age of the animals. These results suggest that NA synthesis may be relatively low in intrapineal sympathetic nerve fibers and that the NA required for the regulation of pineal melatonin synthesis may, to a large degree, stem from the circulation. In addition to nerve fibres, some rare intrapineal cell bodies exhibited DBH-LI; in 5-month-old rats their numbers did not reveal significant differences between day and night. These cells do not appear to represent pinealocytes. They may be a special population of noradrenergic nerve cells perhaps belonging to an as yet unknown intrapineal regulatory system.     

l-Malic Acid Fermentation by Mixed Culture of Rhizopus arrhizus and Proteus vulgaris

When Rhizopus arrhizus NRRL 1526 was mix-cultured with Proteus vulgaris AHU 1144, a strain having a high fumarase activity, in a medium containing glucose as a substrate, fumaric acid fermentation was successively converted to l-malic acid fermentation and large amounts of l-malic acid were accumulated as an end product.

As an inoculum of P. vulgaris for this fermentation, cells in the stationary growth phase (48 to 72 hr culture) were much more favorable than those in the exponential growth phase (18 hr culture) and malic acid yields in the former case were as high as about 70 to 75 % based on initial glucose after 3 to 4 days of the mixed culture.     

Neuropeptide Y and sympathetic vascular control in man

A parallel increase in systemic plasma levels of neuropeptide Y (NPY)-like immunoreactivity (LI) and noradrenaline (NA) was found during thoracotomy and surgery involving cardiopulmonary bypass in man. Thus, plasma levels of NPY-LI increased from 29 +/- 4 pmol/l before anaesthesia to 59 +/- 10 after thoracotomy and to 87 +/- 8 pmol/l upon cardiopulmonary bypass. The corresponding NA levels increased from 1.3 +/- 0.1 nmol/l before anaesthesia to 3.0 +/- 0.6 and 4.2 +/- 5 nmol/l after thoracotomy and cardiopulmonary bypass, respectively. A significant correlation was found between plasma levels of NPY-LI and NA during the operation but not between NPY-LI and adrenaline. The NPY-LI in human plasma was found to be similar to synthetic porcine NPY on reversed phase high performance liquid chromatography. Human submandibular arteries contained high levels of NPY-LI (24 +/- 3 pmol/g). In in vitro experiments on isolated human submandibular arteries, NPY in low concentrations (1000 pmol/l) was found to potentiate the contractile effects of NA or transmural nerve stimulation and to exert vasoconstrictor activity per se in higher concentrations. The calcium-entry antagonist nifedipine abolished both the NPY-induced contractions and the enhancement of NA-evoked contractions. NPY depressed the nerve stimulation-evoked 3H-NA release from human submandibular arteries via a prejunctional mechanism which was resistant to nifedipine. NPY contracted human mesenteric veins and renal arteries, but not mesenteric arteries. In conclusion, NPY seems to be co-released with NA upon sympathetic activation in man. Furthermore, NPY exerts both pre- and postjunctional effects on sympathetic control of human blood vessels.     

Histochemistry of non-specific phosphatases: the use of p-nitrophenyl phosphate and -glycerophosphate as substrates

Synopsis It has been found that the acid and alkaline phosphatases in homogenates of respectively intestine and hypodermis ofAscaris suum hydrolyse sodiump-nitrophenyl phosphate at about twice the rate of sodium -glycerophosphate. This difference was also observed histochemically. Thus, when sections of intestine were incubated for acid phosphatase withp-nitrophenyl phosphate as substrate, the intensity of staining was about twice as great as that obtained after incubation in -glycerophosphate. Further, alkaline phosphatase was evident in sections of hypodermis after only 2 hr incubation inp-nitrophenyl phosphate but was not apparent after 10 hr incubation with -glycerophosphate. Hence biochemical assays and histochemical studies both indicate thatp-nitrophenyl phosphate is a superior substrate to -glycerophosphate for the visualization of acid and alkaline phosphatases in tissues.This paper was presented in part at the 1969 Aberdeen meeting of the British Society for Parasitology.     

Effect of filtering activity of Dreissena polymorpha (Pall.) on the nutrient budget of the littoral of Lake Mikołajskie

The effect of filtering activity of D. polymorpha on nutrient dynamics in Lake Mikoajskie depended mostly on population density: D. polymorpha was important in N and P cycling in periods when its population density was medium or high. The amounts of N and P accumulated in mussel populations at medium density may be similar to those in emergent and submerged macrophytes. However, mussels remove nutrients from cycling matter for a much longer time than do macrophytes. The amounts of nutrients accumulated in a mussel population are several times lower than the quantities which flow through it.