摘要:

Intraduodenal administration of oleic acid increased plasma neurotensin‐like immunoreactivity (p‐NTLI). The integrated responses to saline and oleic acid were 5.7 and 9.7 nM0–180respectively. The integrated response was not significantly altered by i. v. administration of atropine, guanethidine, mepyramine, cimetidine, methysergide or a substance P antagonist, but it was abolished by hexamethonium and morphine (5.9 and 6.3 nM0–180respectively). An exogenous supply of bile and pancreatic juice did not alter the integrated response in morphine‐and hexamethonium‐treated rats. Haloperidol significantly increased the p‐NTLI response to oleic acid (13 nM0–180min). The results suggest that the release of neurotensin is influenced by nervous pathways involving nicotinic and opioid receptors. Catecholamines and 5‐HT receptors may exert an inhibitory influence on th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07475.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The pelvic nerve, carrying parasympathetic nerve fibres, distributes bilaterally in the rat urinary bladder. Preganglionic parasympathetic denervation (decentralization) on one side and postganglionic parasympathetic denervation on the other are followed by an initial decrease in acetylcholine forming capacity and in number of acetylcholinesterase positive nerves in the bladder. However, within a few weeks a marked recovery in acetylcholine synthesis and in number of nerves, based on collateral sprouting, occurs. In this study muscle strips of the rat urinary bladder exposed to the combined surgical procedure was studied. The strips were taken from “denervated” and “decentralized” halves of the bladder. Their contractile responses to methacholine and transmural electrical field stimulation were isometrically recorded in vitro. A supersensitivity to methacholine was found to have developed, of about the same degree, in the two halves 1 week postoperatively. In the denervated halves 4 weeks postoperatively, the supersensitivity was even more marked, whereas in the decentralized halves it tended to be less than after 1 week. The responses of denervated halves to electrical stimulation were reduced 1 week postoperatively. This was also the case for decentralized halves, although the reduction was not large enough to be significant. When examined 4 weeks postoperatively the responses, in particular in denervated halves, were enlarged compared to those 1 week postoperatively. The atropine‐sensitive portion of the responses increased with time. Increases in contractile responses to electrical stimulation accompanied by a tendency to desensitization to methacholine are taken as functional evidence for outgrowth of decentralized parasympathetic neurones in the decentralized halves. The gradual development of sensitization with time may in part explain the increasing responses to electrical stimulation in the denervat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07476.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The resistance vascular function in normotension, and its alterations in primary hypertension and ordinary aging, was analysed concerning the interactions between (1) geometric vascular design, (2) wall distensibility, (3) transmural pressure and (4) smooth muscle activity. Paired hindquarter perfusions were used, comparing hemodynamic resistance characteristics in young, adult and old normotensive (WKY) and spontaneously hypertensive rats (SHR). From the experimental data pressure‐resistance diagrams were constructed, which quantitatively interrelate the four factors in all SHR‐WKY groups. The diagrams show, over a wide pressure range, how altered smooth muscle activity as well as structural adaptation affect resistance vessel distensibility: likewise how distensibility considerably interferes with “active” resistance adjustments. They also show how markedly the range of active resistance responses during ordinary constant‐pressure perfusion is affected whenever pressure is reset to new levels. Finally, the diagrams illustrate the fundamental hemodynamic difference between hypertensive and normotensive resistance vessels, mainly because of factors 1 and 2, which render the hypertensive vessels stronger, stiffer and hyperreactive. Thereby they are capable of a widened response range despite the higher pressure level, which is further accentuated on acute pressure normalization. In contrast, ordinary aging alters resistance vascular behaviour only little, smooth muscle contractility and sensitivity remaining almost unchanged. However, vascular reactivity is moderately enhanced at lower pressures, presumably a geometric consequence of age‐dependent, intimal‐interstit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07477.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The mechanisms affecting renal blood flow and filtration during and after unilateral ureteral obstruction (UUO) are incompletely understood. Since ureteral obstruction leads to changes in interstitial pressure and volume, and since we have previously shown that interstitial pressure conditions can modulate the sensitivity of the tubuloglomerular feedback (TGF) control system, we sought in the present study to define the contribution of the TGF system to changes in GFR during and after UUO, and to observe associated changes in pressures in vessels, tubules and the interstitial space. Interstitial pressures and glomerular filtration rate (GFR) were measured in one group of Sprague Dawley rats. Interstitial hydraulic pressure was determined with a thin catheter placed in the subcapsular space. Interstitial oncotic pressure was estimated from the protein concentration in collected hilar lymph. In a second group of rats proximal tubule pressure (PT) and stop‐flow pressure (PSF) were measured during the first three hours of UUO and after 24 h UUO. In a third group of rats PSF was measured while the loop of Henle was perfused at different rates. The sensitivity of the TGF system was determined from the maximal drop in stop‐flow pressure (APsF) and the turning point (TP)‐the tubule perfusion rate at which 50% of this maximal stop‐flow pressure response was obtained. In a fourth group of rats proximal tubule flow‐rate was measured after release of 2 hrs UUO. The results show that PTand PSFare both increased during the first three hours of obstruction and that they return to normal or sub‐normal levels after 24 h of UUO. Interstitial hydraulic pressure increased to 7 mmHg (control 3 mmHg), and oncotic pressure in the interstitial space decreased to ‐2 mmHg (control ‐3 mmHg) during obstruction. In this situation feedback sensitivity was reduced or abolished. After release of obstruction, interstitial hydraulic pressure fell to zero and oncotic pressure returned to ‐3 mmHg. In this situation feedback sensitivity was increased considerably, with a TP of 12.5 nl/min (control 20.0 nl/min) and a ΔPSFof 12.6 mmHg (control 8.2 mmHg). Thus the present experiments show that during UUO the feedback response is abolished. Diminution of feedback mediated vasoconstriction may contribute to the vasodilation seen during the first hours of ureteral obstruction. Furthermore, after release of UUO an increase feedback sensitivity may be a factor causing the observe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07478.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The parasympathetically denervated and distended rat urinary bladder was found to have increased fourfold in weight when examined 3 weeks postoperatively. Both in muscularis and mucosa of such a bladder the synthesis of proteins, RNA and DNA was increased severalfold. An increase in the polyamines putrescine, spermidine and spermine was also found; these polyamines are usually linked to protein synthesis. The results suggest that the cells of the two layers increase both in size and number. Hyperplasia was, in a previous study, suggested as a possible explanation for a right‐ward shift of the active length‐tension curve of muscle strips in the denervated rat urinary blad

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07479.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In 13 normotensive 50‐year‐old men arterial plasma vasopressin (11.3 ± 2.1 ng/l, mean ± SE) was significantly increased over venous (7.8 ± 1.4 ng/l) in the supine position with an arteriovenous difference of 3.5 ± 1.2 ng/l (p<0.05). After 30 min in the upright position, an average increment of 45% to 11.3 ± 1.8 ng/l was observed for venous vasopressin. Since a similar increase was not found for arterial vasopressin, the arteriovenous difference decreased with 29% to 2.5 ± 2.1 ng/l and was no longer statistically significant. The correlation between supine and standing vasopressin was statistically significant both for arterial (p<0.001) and venous plasma (p<0.05). These data indicate a substantial removal of plasma vasopressin by receptors even in the peripheral vascular beds (forearm) and not only in the liver and the kidneys as previous literature claims. The arteriovenous difference decreases in the upright position, most likely because of reduced plasma vasopressin

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07480.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The administration of a stable adenosine analogue, L‐N6‐phenylisopropyladenosine (LPIA, 0.3 mg/kg i. p.), caused a decrease in the accumulation of L‐DOPA in the rat hippocampus after blockade of aromatic amino acid decarboxylase by NSD 1015 (150 mg/kg). Conversely, the adenosine receptor antagonist theophylline (15 mg/kg) increased the L‐DOPA accumulation. In slices from rat hippocampus L‐PIA causes an inhibition of the stimulation‐evoked release of [3H]‐noradrenaline (NA). The magnitude of this effect was enhanced after 1 week treatment with theophylline (15 mg/kg/day). The number of beta‐adrenoceptors in the rat hippocampus, measured by binding of [3H]‐dihydroalprenolol was significantly reduced after theophylline treatment, and tended to be higher after LPIA treatment. The results show that activation of adenosine receptors in vivo causes a decreased synthesis of NA in the rat hippocampus. The reason may be a reduced firingrate of the NA‐neurons. Theophylline, by contrast, enhanced the synthesis, possibly indicating a role for endogenous adenosine in the regulation of NA‐turnover. Long‐term treatment with these drugs caused adaptive changes in the presynaptic adenosine receptor activity and in the numbe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07481.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

We studied changes in breathing pattern and mouth occlusion pressure (P0. 1) in 11 healthy subjects performing graded steady‐state exercise on a cycle ergometer up to the maximal load sustainable for 4 min. With increasing work intensity both the tidal volume (VT) and end‐inspiratory volume relations to inspiratory (TI) and expiratory (TE) durations were linear in the moderate work load range; in the high load range VTand end‐inspiratory volume tended to plateau with further decreases in TIand TE. The ratio of TIto total breath duration (TI/Ttot) increased with work intensity. Intraindividual coefficients of variation for VT, breathing frequency (f), mean inspiratory flow (VT/TI), and other respiratory variables decreased with increasing work intensity, indicating that breath‐tobreath variations in breathing pattern became smaller as the level of ventilation increased. P0,1rose with VT/TIas a power function with an exponent averaging 1.5 (range 1.3‐1.9), indicating that the ratio P0, 1(VT/TI), an index of respiratory system impedance, increased with VT/TIand work intensity. We conclude that in moderate and heavy exercise (1) the work of inspiration at a given ventilation is reduced because of the increase in TI/Ttot, (2) the impedance of the respiratory system increases with work intensity because of both an increase in f and a flow‐dependent rise in airway resistance, and (3) the neuromuscular inspiratory activity is reflexly augmented because of internal flow‐resi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07482.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of centrally administered neuropeptide Y (NPY) on the sleep‐wakefulness cycle have been studied by analyzing its action in different strains of rats with or without spontaneous hypertension and during two different phases of the circardian cycle. Normal adult Sprague‐Dawley (SD), Wistar‐Kyoto (WKy) and spontaneous hypertensive (SH) rats were used. By means of EEG electrodes the recording of the fronto‐parietal electrocorticogram and the electromyogram could be made. Stainless steel cannula were also implanted into the lateral ventricle. The effects of an intraventricular injection of NPY (1.25 nmol/rat) was compared with the effects of the vehicle (saline) alone. The EEG patterns were classified as desynchronized, mixed or synchronized. In the SD rats NPY produced behavioural signs of sedation and a significant reduction of synchronizeded EEG activity as well as significant increase of synchronized and mixed EEG activities in comparison with the saline treated rats. In the WKy rats NPY administration produced an increase of synchronized EEG activity during evening sessions. In SH rats NPY produced a significant increase of desynchronized EEG activity and a decrease in mixed EEG activity indicating an awakening effect of the peptide. In view of the NPY innervation of the locus ceruleus, it therefore seems possible that the neuronal and hormonal regulation of the locus ceruleus noradrenaline nerve cells is different in the two strains of rats. It also seems possible that the ability of NPY to increase wakefulness in hypertensive animals is related to abnormal changes in the α2‐adrenoreceptors taking place

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07483.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Purified natural porcine gastric inhibitory polypeptide (GIP), in high concentrations, was found to stimulate outflow of45Ca, increase cellular accumulation of cyclic GMP and cyclic AMP and cause release of amylase from dispered pancreatic acinar cells. Synthetic GIP increased cellular cyclic AMP levels, but did not affect outflux of calcium, cellular levels of cyclic GMP or release of amylase. The discrepancy between results with natural and synthetic preparations of porcine GIP may be explained by a possible contamination of natural GIP with cholecystokinin. Other examined pancreatic secretory stimulating peptides which induce cyclic AMP accumulation in acinar cells, also increase release of amylase. Synthetic GIP increased levels of cyclic AMP without affecting amylase release. This suggests that the correlation between amylase release and total cellular accumulation of cyclic AMP in response to GIP is not close.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07484.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY