摘要:

The hydrodynamic properties of the rat bladder in the collection phase were examined by slow continuous and very fast stepwise cystometry in nine rats.In vivo, the fast volume steps induced a reproducible detrusor contraction (type A) which remained after spinal anaesthesia and anticholinergic treatment, but ceased post‐mortally within 1 h. No significant effect of anticholinergic treatment was found on bladder stiffness. The stiffness and relaxation time of the bladder wall increased markedly at large distension. At small and moderate distension, however, the compliances evaluated from continuous and stepwise cystometry were nearly the same, and a linear elastic model of the bladder was applicable. We consider that the rat bladder will be a useful experimental model in further research on viscoelasticity and instability of the bladder wal

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10622.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The hydrodynamic properties of the urinary bladder in rat were examined by means of very small periodic changes in volume at different frequencies. The elastance increased with increasing frequency of volume changes, indicating the presence of viscoelastic elements. When the bladder was only moderately distended the influence of viscosity was minor. We consider that the rat bladder examined by this technique is an ideal experimental model for assessment ofin vivoeffects of pharamacological agents on bladder wall tonus. For example, cholinergic treatment showed a 100% increase in elastance and atropine inhibited this effect completely within 3 min.

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10623.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

125I‐labelled α rat atrial natriuretic peptide (28 amino acids: Ser 99–Tyr 126) ([125I]α‐rANP) was given i.v. to Sprague—Dawley rats and the distribution of radioactivity in the tissues was examined by whole‐body and microautoradiography at intervals from 2 min to 4 h after the administration. Inhibition of uptake of the [125I]α‐rANP by simultaneous injection of an excess of non‐labelled α‐rANP was taken as an indication that highly labelled structures in rats injected with [125I]α‐rANP alone are due to an abundance of specific receptors for the peptide. In the rats given only the [125I]α‐rANP a rapid and high radioactivity occurred in the renal glomeruli, the endocardium of the heart ventricles, the endothelium of the processus ciliares of the eyes, the portal vessels and a few larger vessels of the liver, the subcapsular vessels of the adrenal glands and the parenchyma of the lungs. Other tissues showing a distinct, but less prominent, radioactivity were the endocardium of the heart atria, the walls of the great afferent and efferent vessels in the thoracic cavity, the choroid plexuses of the brain ventricles, the pia mater, brown fat, the muscularis layer of the stomach and the intestines, the lamina propria of the villi in the small intestine and the walls of a few small blood vessels in the kidney medulla. The specific labelling was highest at 2 min after injection and then diminished at later intervals.Several of the labelled structures are localized in tissues involved in the regulation of blood pressure, and fluid and electrolyte homeostasis, processes in which the atrial peptides are considered to play a role. It is suggested that high concentrations of receptors are present at the sites at which the [125I]α‐rANP was strongly localized and that biological effects of the atrial peptides are

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10624.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Fifteen patients (eight men, seven women) with hypertension and renal artery stenosis underwent dilation of the stenosis by percutaneous transluminal renal angioplasty (PTRA). During and shortly after this treatment the effects on the renin—angiotensin—aldosterone system and blood pressure were studied. Plasma renin activity (PRA) was measured in peripheral blood and in renal venous blood during the PTRA. PRA increased in peripheral blood during PTRA as a result of an immediate significant rise in renal venous plasma renin activity by 132 ± 134% (P<0.01) on the dilated side. PRA in the contralateral renal vein was close to that in peripheral blood. Within 10 min after PTRA there was a significant increase in serum aldosterone from 439 ± 343 to 774 ± 635 pmol l−1(P<0.025), while serum cortisol remained unchanged. The aldosterone increase was most probably mediated by angiotensin II. Systolic and diastolic blood pressures were unchanged during PTRA in spite of renin and aldosterone increases, suggesting that antihypertensive factors counteract the pressor effects of a physiologically relevant increas

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10625.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

This study was undertaken to investigate the influence of the arterial baroreceptors on the response of renal sympathetic nerve activity (rSNA) during naloxone‐precipitated morphine abstinence in rats. In chronically baroreceptor‐denervated, morphine‐dependent rats, rSNA, mean arterial pressure (MAP) and heart rate (HR) were studied before and after repeated i.v. bolus doses of naloxone (0.005–5 mg kg−1), during chloralose anaesthesia or in the conscious state.In the anaesthetized animals, naloxone doses of 0.05–5 mg kg−1caused a pronounced inhibition of rSNA, reaching a level 61 % below pre‐naloxone activity. This was accompanied by increases in MAP and HR. In the conscious rats, the lower doses of naloxone elicited an initial state of increased somatomotor activity. This was paralleled by slight increases in rSNA and MAP. After 4–5 min, the behavioural excitation faded and was replaced by lethargy. The rats exhibited still signs of withdrawal in the form of piloerection, chromodacryorrhoea and defaecations. Concomitantly, rSNA returned towards the pre‐naloxone level, while MAP showed a sustained increase. The higher naloxone doses exacerbated the hypertension without any further changes in rSNA or in behaviour.We conclude that the influence of the baroreceptors is of minor significance for the inhibition of rSNA during naloxone‐precipitated abstinence in anaesthetized rats. In conscious, intact rats, however, the baroreceptors seem to contribute to rSNA inhibition since no significance decrease of rSNA occurred in baroreceptor‐denervated rats in the present study. This is in contrast to our previous finding of a marked inhibition of rSNA in rats wi

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10626.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Central haemodynamics were studied in one group of morphine‐dependent rats, and in a non‐dependent control group, before and after administration of repeated bolus doses of naloxone. Dependence was induced by s.c. morphine pellet implantations. Mean arterial pressure (MAP), heart rate (HR), cardiac output (CO) and mean transit time (MTT) were measured in the conscious state, after induction of chloralose anaesthesia and after the administration of naloxone (0.005, 0.05>0.5 and 5 mg kg−1i.v.). Total peripheral resistance (TPR), stroke volume (SV) and central blood volume (CBV) were subsequently calculated. The haemodynamic variables did not differ significantly in the conscious state, except for a lower SV, when compared with the non‐dependent control group. However, in response to anaesthesia the dependent rats exhibited a greater fall in MAP, mainly due to a TPR decrease. Naloxone elicited a marked increase in MAP in the morphine‐dependent group, which was mainly caused by an increase in TPR. Naloxone induced no significant change compared with the control group in CO and CBV, while SV increased concomitantly with a lowered HR after naloxone in the morphine‐dependent group. These results suggest that the withdrawal hypertension during morphine abstinence was mainly explained by an increase in TPR, reflecting an augmented tone of the resistance vessels. The minor changes in CBV indicate that the tone of the venous capacitance vessels was largely unaffected by naloxone‐induced morphi

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10627.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The effect of acute normovolaemic haemodilution on microvascular red blood cell flow was studied by intravital microscopy in the tenuissimus muscle of the rabbit. Blood was substituted isovolaemically with equal volumes of a 6% solution of dextran 70 (MW 70,000). The systemic haematocrit (Hsys) decreased from 36±4% (mean±SD) to 17 ± 2%. Following haemodilution capillary haematocrit (Hcap), as measured by video densitometric methods, decreased by 20 ± 9%. The reduction ofHcapwas significantly smaller than that ofHsys, andHcapnormalized with respect toHsysincreased from 0.39 ± 0.07 in the control situation to 0.62 ± 0.18 after haemodilution. Red blood cell velocity (vrbc) increased by 45 ± 20% and compensated for the decrease inHcapin such a way that the red blood cell flux, calculated fromvrbcandHcap, remained unchanged. Measurements of volume flow in the feeding arterioles in the muscle revealed a fractional redistribution of blood flow in favour of the muscle capillaries following haemodilution at the expense of vessels in adjacent connective tissue supplied by the same arterioles. This fractional flow redistribution was likely the basis for the relative increase in capillary haematocrit seen after haemodilution. The present data demonstrate that an acute reduction of the systemic haematocrit is compensated for in an active regulating vascular bed by a proportionally smaller decrease in capillary haematocrit and by an increased capillary red cell velocity. Microvascular haematocrit was found not to be a constant fraction of the systemic value, which supports the view of capillary haematocrit as a ‘controlled’ physiologica

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10628.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Subcutaneous blood flow (SBF) was studied simultaneously in the upper arm at heart level and in the lower limb during positional changes and during leg exercise in seven healthy males. SBF was estimated by local clearance of133Xenon registered by portable cadmium telluride detectors. Venous pressure was recorded directly on dorsum on the foot. Changing the position from supine to head‐up tilt, SBF decreased by 43% (P<0.01) at the arm level, 40% at the thigh (P<0.01), 47% at the calf (P<0.01) and decreased by 51 % at the ankle level (P<0.01). Performing 20 heel‐raisings per min in nearly erect posture, SBF increased by 96% at the thigh (P0.1). At 40 heel‐raisings per min SBF increased by 99% at the thigh (P<0.01), 121% at the calf (P0.1). During leg exercise subcutaneous vascular resistance was significantly increased at arm and ankle levels. In contrast, a vasodilatory response was noticed at the thigh and calf levels and seemed associated with a decrease in local venous pressure to below the trigger level of the sympathetic veno‐arteriolar reflex mechanism. In conclusion, SBF in the lower limb of man was increased during exercise. The increase in SBF could only partly be ascribed to the concomitant increase in perfusion pressure. The local blood flow response seemed modified by changes in sympathetic nervous activity and metabol

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10629.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Nicotine‐exposed and control rats were compared with respect to contractile, enzyme‐histochemical and biochemical properties of fast‐ and slow‐twitch skeletal muscles in order to elucidate the mechanisms underlying previously observed effects of tobacco smoking on skeletal muscle. The nicotine was administered in drinking water, since this approach has been shown to result in a plasma nicotine pattern similar to that seen in tobacco smokers. In a pilot study, fibre‐type proportions and mitochondrial enzyme activities tended to change in the slow‐twitch soleus muscle after 9 weeks of nicotine exposure in a way similar to that previously reported in tobacco smokers. In the present study, the duration of nicotine exposure was more prolonged (18 weeks) and the number of studied animals was increased. In this series neither contractile, enzyme‐histochemical nor biochemical properties were affected by the nicotine exposure. It is thus concluded that prolonged nicotine exposure has no significant effect on the skeletal muscle characteristics studied, and that other aetiological agent(s) for the observed differences in such characteristics between smokers and non‐smokers should

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10630.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Somatostatin has been found to induce apnoea when applied into the brain ventricular system (Fuxeet al. 1982, Härfstrandet al. 1985). The site of action of somatostatin was suggested to be in the dorsal respiratory neurons in the medulla oblongata of the rat (Fuxeet al. 1982) where high somatostatin‐like immunoreactivity has been detected (Kaliaet al. 1984a). In the present study we wanted to further localize the site(s) of action of somatostatin on respiration by microinjection of somatostatin into the medulla oblongata of the cats. We could not detect any inhibitory effect of somatostatin on respiration after microinjection into the nuclear complex of the solitary tract. On the other hand microinjection of somatostatin into the region of nucleus paragigantocellularis lateralis consistently caused apnoea. This finding further supports the idea that this structure functions as an integrative area of respiratory drive inpu

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1988.tb10631.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY