摘要:

We have studied the ontogeny of Na‐K ATPase‐mediated Na and K transport in rat renal proximal tubular cells using electron probe analysis. The cells were cultured from kidneys of 10‐day‐old, young (Y), and 40‐day‐old, adult (A) rats. Before an experiment cells were Na‐loaded and K‐dcpleted by incubation in K‐free medium. The maximum rate of ouabain‐sensitive Na and K transport was measured after reactivating the Na‐K pump by transferring the cells from K‐free medium to medium containing 5 mM K. In cells cultured for 2 days, ouabain‐sensitive Na and K net initial transport rates were significantly higher in A than in Y cells. Between 2 and 4 days in culture there was a significant decrease in ouabain‐sensitive Na and K transport rates in both Y and A cells. From 2 to 4 days of culture there was, in Y but not in A cells, a significant decrease in K/Na ratio. The decrease in K/Na ratio was due to a significant increase in Na content. After incubation in K‐free medium, net intracellular solute accumulation was observed in A and Y cells cultured for 4 days but not in A and Y cells cultured for 2 days.In conclusion, maximal Na‐ and K‐pump‐mediated transport increases during terminal differentiation. This increase can be measured in cells cultured for 2 days. With longer time in culture, Na K pump activity decreases and the difference between A and Y cells is not measurable. We had previously observed that net Na and K permeabilities decrease from 2 to 4 days in culture in A but not in Y cells. In Y cells cultured for 4 days, a decrease in pump activity without a change in Na and K permeability causes an i

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08309.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

This study was performed in order to quantify the effects of renal venous pressure (RVP) elevation on absolute and fractional reabsorption rates of sodium and water in proximal and distal segments of the nephron in dog kidneys. Renal blood flow (RBF) was measured electromagnetically. Clearance of [51Cr]EDTA was used as a measure of the rate of glomerular filtration (GFR). GFR, urinary excretion rates of sodium and water, and lithium clearance were used for assessing the absolute and fractional reabsorption rates of sodium and water in the proximal as well as in more distal segments of the nephron. In the kidneys with intact innervation RVP elevation to 19.9±0.1 mmllg caused significant increases in both absolute (APR) and fractional (FPR) proximal reabsorption rates from 33.4 ± 4.2 to 38.7 ± 2.0 ml min and from 0.62 ± 0.04 to 0.71 ± 0.04, respectively. These responses were unaffected by acute surgical denervation of the kidneys. In contrast, chronic renal denervation or infusion of phentolamine (5 μg kg‐1min‐1) into the renal artery eliminated the increase in APR and FPR during RVP elevation to 20 mmHg. Chronic, but not acute renal denervation depleted renal tissue content of adrenaline and noradrenaline. The results suggest that the increase in APR and FPR during RVP elevation is due mainly to local sympathetic reflex m

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08310.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

We investigated the direct pancreatic effects of noradrenalinein vivoon the secretion of insulin, glucagon, and somatostatin from thein situpancreas in halothane‐anaesthetized dogs. Noradrenaline was infused into the superior pancreatic artery at 12 ng min‐1, a rate that did not alter systemic glucose or noradrenaline levels nor heart rate or blood pressure. This pancreatic infusion of noradrenaline did not affect the basal pancreatic output of insulin, yet did markedly inhibit arginine‐stimulated insulin secretion. The acute insulin response (AIR) to an intravenous injection of arginine (2.5 g), which was 4293 ± 1260 μU minlunder control conditions, was reduced to 1054 ± 396 μ min‐1by noradrenaline (P<0.01). Noradrenaline increased basal pancreatic glucagon output from 321 ± 130 pg min‐1to 876 ± 309 pg min‐1after 20 min of infusion (P<0.05) and the acute glucagon response (AGR) to arginine, being 1033 ± 203 pg min‐1under control conditions and 1746 ± 249 pg min‐1during noradrenaline infusion (P<0.05). The basal output of somatostatin did not change during noradrenaline infusion, but arginine‐stimulated somatostatin secretion was impaired. The acute somatostatin response (ASLIR) to arginine was 473 ± 124 fmol min‐1under control conditions and was decreased to 140 ± 80 fmol min‐1by noradrenaline (P<0.01). We conclude (1) that insulin and somatostatin secretion are regulated similarly by noradrenalinein vivo, (2) that B cell and D cell sensitivity to noradrenaline depends on the degree of secretory stimulation: while basal secretion is not affected, arginine‐stimulated secretion is inhibited, and (3) that both basal‐ and arginine‐stimulated glucagon secretion a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08311.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The isolated (denervated) parabiotically perfused rat jejunum was characterized for base‐line haemodynamics, autoregulation of blood flow and oxygen consumption and long‐term (3 h) stability with respect to both haemodynamics and the absence of tissue injury. In short‐term experiments, the parabiotically perfused preparation autoregulated oxygen consumption but not blood flow over a wide range of perfusion pressures (25–85 mmHg). When the intestinal segment was subjected to near total ischaemia for 1 h, followed by 1 h of reperfusion, mucosal injury was induced which could be prevented by i.v. administration of superoxide dismutase after ischaemia just prior to reperfusion, or allopurinol prior to ischaemia. These findings support the concept of post‐ischaemic reperfusion injury in the denervated preparation without hepatic ischaemia. This preparation could thus serve as an improved model for the study of the pathophysiology of post‐ischaemic reperfusion injury in the ra

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08312.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Histochemical and immunocytochemical methods were used to study the presence of carbonic anhydrase (CA) isoenzymes in the caecum and colon of normal and germ‐free rats. Very high enzyme activity was demonstrated by histochemistry in the caecum and proximal colon of normal rats, while the activity decreased in the distal colon. Very strong immunostaining for the isoenzyme CA I was found in the cytoplasm of surface cells and upper gland cells in the caecum and colon of normal rats. In the distal colon the staining was less intense with a marked cell‐to‐cell variation. Ca II was found in the apical (luminal) cell region of the surface epithelium in all regions. Ca III was possibly present in small amounts, but this could not be judged with certainty. There was no difference in carbonic anhydrase between normal and germ‐free rats (except for less staining of the mucosal capillaries in germ‐free animals). Therefore, our data give no support to the hypothesis that CA I participates in the absorption of microbial fermentation products. The location of CA II in the apical cell region suggests a role for this isoenzyme in regulation of the microclimate close to the epithel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08313.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Insulin‐like growth factor I (IGF‐I; somatomedin C) is a trophic peptide of importance for the development of several tissues and organs. In the present study we have mapped the cellular distribution and dynamic changes of IGF‐I immunoreactivity in the rat cerebellum from its postnatal development to maturity.In vitrohybridization of IGF‐I mRNA was used to demonstrate that the IGF‐I immunoreactive material was synthesized in the cerebellum during a limited time period of cerebellar differentiation.IGF‐I immunoreactivity was absent in primordial nerve cells but was present in neuroglial cells during the first two days after birth and then rapidly increased in intensity in the latter during the next few days. Proliferative nerve cells in the external granular layer did not express IGF‐I immunoreactivity, while migrating and differentiating nerve cells as well as neuroglial cells showed intense labelling. Starting about 2 weeks postnatally, the IGF‐I immunoreactivity declined, first in the neuroglial cells and eventually in the nerve cells. No IGF‐I immunoreactivity could be demonstrated in the normal adult cerebellum. Colchicine pretreatment did, however, enable demonstration of IGF‐I immunoreactivity in adult cerebellar nerve cells but not in neuroglial cells.In vitrohybridization revealed IGF‐I mRNA in the developing cerebellum but only at very low levels in the adult cerebellum.It is concluded that IGF‐I is likely to be a factor of importance for the development and maturation of nerve cells and neuroglial cells in the brain. The neuroglial cells in normal adult cerebellum as well as in other parts of the central nervous system do not show any IGF‐I immunoreactivity, in contrast to neuroglial cells in the automatic and p

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08314.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Substance P receptors were examined in crude synaptosomal fraction preparations of the rat spinal cord using [125I]Bolton Hunter Substance P ([125I]BHSP) which binds with an affinity of 0.043 ± 0.015 nM. The concentration of binding sites in the dorsal and in the ventral part was 4.55 ± 0.86 and 2.35 ± 0.35 fmol mg‐1respectively. GTP inhibited the specific binding of [125I]BHSP in a concentration dependent manner, with io‐3mol I‐1GTP yielding 89–90% inhibition and io‐5mol l‐1GTP producing 50% inhibition. This value was similar in dorsal and ventral spinal cord. The effects on SP receptors of chronic treatment with the tricyclic antidepressant imipramine (2 × 10 μmol kg‐1day‐1p.o. 14 days) and the specific5‐I IT (serotonin) uptake blockers alaproclate (2 × 20μmol kg‐1day‐1p.o. 14 days) and zimelidine (2 × 10μmol kg‐1day‐1p.o. 14 days) were examined in the ventral spinal cord, where SP and 5‐IIT coexist in the terminals of descending neurons from the raphe nucleus. Zimelidine treatment was found to cause a significant reduction in the number of substance P binding sites in the rat ventral spinal cord as compared to saline treated controls. These findings are discussed in light of the previous observation (Brodinet al. 1984) that SP levels are significantly elevated after treatment with antidepressant drugs especially with zimelidine, which alters the firi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08315.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The mechanisms underlying the stimulatory effects of capsaicin on the contractility of the guinea‐pig heart were studiedin vitro. Capsaicin (10‐1to 10‐5M) caused an increased overflow of immunoreactive material, suggesting release of calcitonin gene‐related peptide (CGRP)‐and neurokinin A (NKA)‐like immunoreactivity (‐LI), but not of neuropeptide Y (NPY)‐LI from the isolated Langendorff‐perfused whole heart. The capsaicin‐induced release was calcium‐dependent. During exposure to capsaicin, the heart rate was increased, while the contractile force was reduced. In addition to releasing CGRP and NKA‐LI, potassium (60 mM) also increased the overflow of NPY‐LI. The potassium‐induced release of peptides was less calcium‐dependent than the response to capsaicin. Considerably higher tissue levels of CGRP‐LI were found in the atria (about 30 pmol g‐1) than in the ventricles (about 10 pmol g‐1). In experiments on the right atria using transmembrane action‐potential recordings of myocytes, CGRP induced a prolongation of the action potential concomitantly with an increase in rate and contractile force, which was similar to the effect of noradrenaline. Furthermore, CGRP increased the contractile force and relaxation velocity of the electrically stimulated atria. Capsaicin (10‐7M) also increased the duration of the atrial action potential. In conclusion, CGRP‐like material is released by capsaicin from the isolated guinea‐pig heart. Both CGRP and capsaicin prolong the plateau phase of the action potential of atrial myocytes. Therefore, the present data give further evidence that CGRP release from sensory nerves within the heart underlies

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08316.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

To examine the functional significance of early postnatal active sleep for the development of behavioural reactivity to auditory stimuli, rat pups were daily injected i.p. from the 7th to the 18th postnatal days with 5 mg kg‐1(6.6 mmol 1‐1) desipramine or 25 mg kg‐1(12.2 mmol 1‐1) zimeldine. Sleep‐wake behaviour was recorded with a static‐charge‐sensitive bed (SCSB) method. Both desipramine and zimeldine suppressed the percentage of active sleep relative to the total recording time throughout the treatment period. In addition, these drugs increased the percentage of quiet state and waking. At the age of 38 days the zimeldine‐treated rats showed more motor activity in the open field than the controls. At the age of 39 and 78 days all rat groups behaved similarly in the open field. Startle measures and motor activation, provoked by auditory stimulation, were determined by the SCSB method when the rats were 4 months of age. Auditory stimuli, consisting of a series of ten clicks, induced a greater number of startles as well as strong movement responses in the control rats than in the desipramine‐ or zimeldine‐treated rats. The number of small movement responses did not differ between the rat groups. These findings indicate that early postnatal active sleep and the monoaminergic systems regulating it may be important for the normal development of neuronal circuitry associated with later reactivity

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08317.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The aim of the present investigation was to evaluate whether the responses of central catecholamine (CA) neurons to CA receptor blockade by haloperidol are altered upon toluene exposure. Male rats were exposed to air or toluene (80 ppm) for 5 and 4 days, 6 h day‐1. CA levels and utilization were determined in discrete regions of the forebrain and hypothalamus as well as in the substantia nigra (SN) and anteromedial frontal cortex (AMFC). Serum levels of corticosterone, thyroid stimulating hormone, luteinizing hormone and prolactin were determined by radioimmunoassay procedures. Toluene exposure led to increased dopamine (DA) utilization in the AMFC and increased CA utilization in the paraventricular hypothalamic nuclei. In air‐exposed rats haloperidol (1 mg kg‐1, i.p., 2 h before killing) increased DA utilization in the marginal part of the nucleus caudatus putamen (CAUD). In toluene‐exposed rats, haloperidol induced significant depletions of DA stores in the SN and in the medial and central parts of the CAUD. In the posterior nucleus accumbens (ACC) DA utilization was significantly increased. Combined haloperidol and toluene treatment selectively decreased DA levels in the ACC and SN, and significantly increased DA utilization in the CAUD, as compared with the air‐exposed control group. Furthermore, after combined treatment, there was a specific increase in noradrenaline (NA) utilization in the SN and in CA utilization in the medial palisade zone of the median eminence. Serum prolactin levels were substantially raised in both the air and toluene groups after the haloperidol treatment. In conclusion, acute haloperidol treatment preferentially reduces DA levels and increases DA and NA utilization in the SN and in discrete tel‐ and diencephalic areas in rats exposed

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08318.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY