摘要:

AbstractRegional renal and single glomerular blood flow was investigated in rats using 141‐Ce and 85‐Sr labelled microspheres. The kidneys were prepared for micropuncture and also the artery was catheterized with a steel cannula in order to make injections of 133‐Xenon and vasoactive substances selectively into one kidney. The microspheres were first separated by sedimentation into a narrow fraction and then injected as a plasma suspension into the carotid artery; the two batches were infused at half an hour intervals. Single glomeruli were sampled from kidney sections with the aid of silicon rubber casts allowing the identification of the glomeruli both with respect to their localisation and their postglomerular appearance. The results showed a relatively high blood flow in the superficial and juxtamedullary glomeruli of above 100 nl/min per 100 g rat whereas in the other glomeruli the blood flow was about 70 nl/min per 100 g rat. No differences could be observed between the right untouched kidney and the left prepared for micropuncture. Furthermore no discrepancies between the results from the two injections could be found. The data on the total renal blood flow obtained by the 133‐Xenon wash‐out method agreed well with the microsphe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05874.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe possible relationship between changes in electrical and mechanical activity and in tissue levels of cyclic AMP (cAMP) during relaxation of the myogenically active rat portal vein has been elucidated in response to different inhibitory stimuli. Isoproterenol, 10‐5M, caused an initial pronounced inhibition of spike discharge and contractions followed by a partial recovery over the 15 min exposure period. This inhibitory response was associated with doubling of tissue cAMP after 1 min and a less pronounced increase in later measurements (5 and 15 min). Papaverine, 10‐4M, caused, in contrast, an inhibition of electrical and mechanical activity which developed gradually over the entire 15 min exposure period. The levels of cAMP at 1, 5 and 15 min all exceeded the corresponding values obtained with isoproterenol. The two drugs in combination gave a biphasic inhibitory response associated with a sustained large increase in the level of cAMP. These drug induced inhibitions were thus accompanied by increased levels of cAMP, but the different time courses of the electromechanical responses could not be related to corresponding variations in the content of cAMP. Hyperosmolality (+ 150 mM sucrose) and mechanical vibrations (100 Hz) elicited differentiated inhibitions of smooth muscle activity without changes in tissue cAMP. The mechanical effects elicited by isoproterenol, papaverine and hyperosmolality were accompanied by approximately parallel changes in electrical spike discharge. It is concluded that increased levels of cAMP are not indispensible for vascular smooth muscle relaxation, and that the magnitude of pharmacologically induced inhibitions are not always closely related to the total tissue content of the nucleot

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05875.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractGastrin released by electrical vagal stimulation was measured in the portal blood of eviscerated cats. Blood flow was recorded by a drop chamber technique and the total gastrin output calculated. Basal peripheral gastrin levels averaged 65 pg/ml and basal portal levels 225 pg/ml. On unilateral vagal stimulation with frequencies above 3–4 Hz gastrin release rapidly increased, reaching a peak within 5–10 min. In spite of continued stimulation and independent of frequency, the gastrin levels declined and returned to basal values after a total of 2–3 000 stimuli. A new maximal response could be induced first after a recovery period of 15–30 min. In the same cat stimulation of either the left or the right vagus released equal maximal amounts of gastrin (average 32 000 pg). The maximal gastrin output on vagal stimulation corresponds to less than 1% of the total content of antral gastrin determined with radioimmu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05876.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe reflex inhibition of abdominal stretch receptors in crayfish was studied by controlled passive flexion of individual abdominal joints. The results are very similar to those obtained by electrical or mechanical stimulation of individual stretch receptors in immobilized abdomens. Reflex effects from posterior to anterior abdominal segments are somewhat stronger than in the opposite direction. Flexion of one abdominal joint excites the stretch receptors of that joint and inhibits the stretch receptors in neighbouring abdominal segments. Without reflex inhibition flexion of one abdominal joint excites the stretch receptors in several abdominal segments.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05877.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn the present study a comparison was made on the role of the renin‐aldosterone system in rats with various forms of experimental hypertension (pinealectomy‐induced, renal and spontaneous). The plasma sodium and potassium concentrations as well as renin activity were measured. Thein vitroproduction of aldosterone by quartered adrenal glands of these rats was also determined. 5 weeks after the operations the blood pressure of the pinealectomized and renal operated rats was significantly increased. The plasma sodium concentration did not differ in various groups, but that of potassium was decreased in the renal hypertensive animals. The plasma renin activity of the pinealectomized rats was elevated while in other forms of hypertension it was at the control level. The basal aldosterone production by the adrenal quarters was equal in all the groups. ACTH, dibutyryl cyclic adenosine‐3′,5′‐monophosphate (DBA) and 5HT stimulated the aldosterone production. The responses to ACTH and DBA were greater in the adrenals of renal hypertensive rats than in the other forms of hypertension or in the controls. We suggest that the renin‐aldosterone system is of importance in the maintenance of renal hypertension, while in pinealectomy‐induced hypertension elevated plasma renin activity reflects an increased sympathetic activity which probably is the main cause of hypertension i

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05878.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe ventromedial hypothalamus of the unrestrained cat was stimulated electrically through permanent electrodes. The stimulation parameters, amplitude, duration and frequency of the square wave pulses were combined to produce a 20% increase of the resting heart rate value. The total electric charge for each parametric combination was calculated. The charge per stimulation (10 s) varied from about 1 to 100 micro‐coulombs, depending on the parametric combination used. The response could therefore not be expressed as a function of the charge but depended on the individual parametric combinations. The relation among the stimulation parameters and the total amount of electric charge of the pulses was estimated by the correlation technique. The results suggested that about 60% of the variation in the electric charge resulting in the constant response was due to the variation of the pulse repetition frequency. The optimal parameters for eliciting cardio‐acceleration in the cat by stimulation of the ventromedial hypothalamus seem to be pulse durations between 0.1 and 0.5 ms and pulse repetition frequencies below 100 P/s, with pulse amplitude as the dependent varia

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05879.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe action of volleys in contralateral primary afferents on transmission in the la inhibitory pathways to motoneurones was investigated with intracellular recording from motoneurones. Ia IPSPs in flexor as well as most extensor motoneurones were regularly facilitated by volleys in contralateral high threshold muscle, cutaneous and joint afferents in spinal cats under chloralose anaesthesia. In decerebrate cats with a low pontine lesion transmission in la inhibitory pathways was not facilitated but rather depressed by volleys in these afferents. The recurrent effects from motor axon collaterals were investigated on inhibitory transmission from different contralateral afferents to motoneurones. Previous investigations have shown that the interneurones mediating the reciprocal la inhibition receive recurrent inhibition via motor axon collaterals and Renshaw cells. Now a strong positive correlation was revealed between recurrent depression of IPSPs evoked from different contralateral afferents and facilitation of la IPSPs by the same afferent volleys. These results suggest that the recurrent depression of IPSPs from different contralateral primary afferents depends on their excitatory convergence onto the la inhibitory interneurones, which then partly mediate the IPSP evoked in the motoneurone from these afferents.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05880.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractMaterial causing contraction of the isolated rabbit aorta (rabbit aorta contracting substance, RCS) was released from guinea pig lung following perfusion with arachidonic acid and from human blood platelets after addition of thrombin to induce aggregation. Prostaglandin endoperoxides (prostaglandins G2and/or H2) were found both in the perfusate of guinea pig lung (1–3 ng/ml) and in the medium collected after platelet aggregation (13–37 ng/ml). The contractile response of the isolated rabbit aorta to the pure prostaglandins G2and H2, was also determined. These data combined with the quantitative analyses of the endoperoxides released from the lungs and platelets showed that only a minor part of the rabbit aorta contracting activity was due to the prostaglandin endoperoxides. The major part of the activity consisted of very unstable material. The half life of this material was about 30 s at 37d̀ whereas at this temperature the prostaglandin endoperoxides had a half life of about 5

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05881.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe cerebral ventricular system of anesthetized dogs was perfused with synthetic isotonic CSF and, for 80 s intervals, with hypertonic CSF of various compositions. Hypertonic perfusion evoked centrally mediated marked increases in arterial blood pressure, heart rate, respiratory rate, and ventilation and, after some delay, an excitatory resembling arousal. The responses were coordinated in time with the induced CSF hypertonicity, graded in relation to its magnitude, and reversible on return to isotonicity. The effects, which seemed to be elicited from periventricular structures in the brain stem, were more pronounced and consistent when CSF hypertonicity was produced by adding NaCl or Na‐lactate than monosacharides to the isotonic CSF solution. Analysis of the cardiovascular responses indicated that they were caused by increased sympathetic vasoconstrictor and cardiac accelerance fibre activity and by inhibition of vagal discharge to the heart. The described pattern of response much resembles that evoked by physical exercise, a state which might lead to osmolar changes in the brain and CSF of a similar kind to that in the present study as a consequence of the pronounced work‐induced arterial hyperosmolality. It is suggested that such an osmotic mechanism might constitute a “metabolic link” in the centrally mediated circulatory and respiratory adjustments in e

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05882.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractParenchymal rat liver cells were isolated by a modification of the collagenase method of Quistorff, Bondesen and Grunnet. The cells secreted albumin into the medium and incorporated14C‐leucine both into cell proteins and proteins secreted into the medium. Albumin production measured from the immunologically determined increment in the incubation medium was 1.7 ± 0.2, μg albumin/min per g liver wet wt. This is about 30% of the rate of production in the perfused liver. Addition of insulin (10‐6‐10‐10M) enhanced albumin production (50‐17%), and incorporation of14C‐leucine both into albumin (50‐8%), secreted proteins (40‐9%) and cell proteins (20‐8%). Insulin does not increase the production of albumin by depleting the cells. The effect of insulin on albumin production is compatible with an effect on the rate of synthesis as the specific activity of albumin is unaffected by

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05883.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY