摘要:

Monoamine oxidase in platelets collected on two different occasions, from twelve apparently healthy subjects, were studied. The influence of human platelet poor plasma (PPP) on MAO thermolability and variation in enzyme activity over time was investigated. A 30–70% reduction of the activity was observed after heat treatment at 52°C for 30 min. Activity of MAO was determined before (C) and after heat treatment (H). No significant differences between the H/C ratios on the two occasions were observed for either Vo, Vmaxor Kmwith or without 10% PPP added to the incubates. A temporal increase of the kinetic parameters was observed. The magnitude of this increase was smaller for vothan for apparent Kmand Vmax. Platelet MAO activity regulation by human PPP is discuss

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07487.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

K‐depletion induced by K‐deficient fodder led to hypokalemia, decreased K‐content and increased Na‐content in skeletal muscle of rats. The heart showed similar, although more modest changes, whereas brain, erythrocytes and liver maintained virtually constant Na–K‐contents. K‐depletion decreased total binding capacity for3H‐ouabain by up to 76%, an effect which could be demonstrated both in vitro and in vivo. Following 3 weeks of K‐depletion, the apparent KDfor3H‐ouabain binding to rat soleus was 1.3times10‐7M as compared to 2.4times10‐7M in controls. Also in mice and guinea pigs, K‐depletion induced a selective loss of K from muscle and decreased3H‐ouabain binding capacity. K‐depletion induced by diuretics or fluorohydrocortisone gave similar effects. The effects of K‐depletion on3H‐ouabain binding capacity were confirmed by measurements of 3‐O‐methylfluorescein phosphatase activity, an enzyme activity which is closely correlated to the Na–K–ATPase activity. Following readministration of K, the K‐contents of plasma and muscle reached control levels in 24 hours, but3H‐ouabain binding capacity was not normalized until after 6 days of K‐repletion. In mammalian skeletal muscle, K‐depletion leads to a marked and reversible reduction in3H‐ouabain binding capacity, which may be

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07488.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Structural and mechanical adaptations in response to sustained changes in arterial pressure were studied on abdominal aorta of the male rat. Two models were used: 1. Aortic ligature (L), immediately below the renal arteries producing hypotension distal to the knot (duration before sacrifice 6 weeks or 3 months). 2. One‐clip renal hypertensive rats (H) (duration 6 weeks). Normotensive sham‐operated rats (C) served as controls. At sacrifice mean tail artery pressure was L: 58±1, C: 110±3, and H: 163±5 mmHg (SE, n=6). Segments of abdominal aorta were mounted in vitro for determination of their length–tension relations (activation: High‐K+solution with 2.5 mM Ca2+). At end of experiments the vessels were supramaximally stimulated at optimal circumference (Io) for active force (activation: High‐K+solution with 10 mM Ca2+, and 10‐5M noradrenaline), and then fixated for light and electron microscopy. Passive and active length–tension relations were shifted towards lower and higher circumference values for hypo‐ and hypertensive vessels, respectively. The Iovalues were L: 3.60±0.13, C: 4.44±0.19, and H: 4.91±0.29 mm. The media thickness at I0was reduced in L: 56.0±3.3, and increased in H: 81.3±2.4 compared to C: 73.4±1.8 μm. Maximal active wall stress was L: 46.6±9.8, C: 74.2±7.0, and H: 83.8±7.7 mN/mm2. Intracellular volume (ICV) in the media was L: 30±2, C: 45±3, and H: 44±1% (n=4 for each). The results indicate that the vascular smooth musle in the H group has an unaltered force generating ability. The low active stress in L could to a large extent be explained by the decreased ICV. In conclusion, the arterial vessel wall of these animals, with no genetic predisposition for hypertension, adjusts smooth muscle content and length–force relations in a characteristic way in response to sustained a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07489.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of TRH on regional blood flow were studied in rabbits under urethane anesthesia. Four types of experiments were performed with the following results. (1) I.v. injection of 2 mg/kg b. w. TRH in animals with unilateral cervical sympathotomy caused a rise in mean arterial blood pressure from 10.0±0.5 to 13.3±0.5 kPa. Total cerebral blood flow, measured with labeled microspheres, increased from 75±5 to 126±16 g/min/100 g tissue on the intact side. There was a similar increase on the side with symphathotomy. The greatest increase, about 70%, was observed in cortical gray matter, caudate nucleus and thalamic region. There were marked reductions in blood flows in the spleen, gastric mucosa, skin and skeletal muscle. Mydriasis occurred on the side with an intact sympathetic supply. (2) I.v. infusion of 0.06 mg/kg b. w. per min TRH in animals with unilateral cervical sympathotomy and stabilized blood pressure increased total cerebral blood flow from 84±10 to 139±7 g/min/100 g. Blood flows to the masseter muscle, submandibular gland and facial skin but not to the eye or tongue were markedly reduced on the side with an intact sympathetic supply while little or no effect was observed on the side with sympathotomy. (3) Unilateral peripheral stimulation of the sympathetic chain at 1 Hz after bilateral sympathotomy caused a reduction in blood flows in the tongue, masseter muscle, submandibular gland and facial skin in animals with stabilized blood pressure. No potentiation of the stimulation effect was observed during TRH infusion. (4) The arteriovenous difference in oxygen saturation in the brain decreased from 39.1±2.8 to 26.4±3.7% after i. v. injection of 2 mg/kg b. w. TRH. The results indicate that TRH caused cerebral vasodilation in excess of that required by possible changes in cerebral metabolism. The vasoconstriction in the head region and the mydriasis was caused mainly by an increase in the activity of the cervical symphathetic

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07490.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

During aortic blood flow obstructions and angiotensin infusion blood may be accumulated in the heart and the lungs because of retention or redistribution of blood from compliant regions. We measured the cardiopulmonary blood volume (CPBV) when left ventricular systolic pressure was raised by about 50 mmHg by angiotensin infusion and by balloon inflation in the ascending and descending thoracic aorta, at control inotropy and during isoproterenol infusion, in 6 anesthetized, closed‐chest dogs. CPBV was calculated from determinations of cardiac output (thermodilution) and the interventricular mean transit time of ascorbate (polarographic determination). Angiotensin always increased CPBV, but the rise was greater at high than at control inotropy (16.5±4.4% and 5.1±1.2%). Balloon inflation in the descending thoracic aorta increased CPBV similarly at high and control inotropy (11.1±2.4% and 16.6±4.0%) whereas CPBV was unaltered or fell during inflation in the ascending aorta at both inotropic levels. Right and left ventricular end‐diastolic pressures rose only during angiotensin infusion and balloon inflation in the descending thoracic aorta. By balloon inflation, cardiac output only fell during blood flow obstruction in the ascending aorta. Thus, an increase in CPBV during these interventions is not due to retention but is caused by redistribution of blood towards th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07491.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Previously we have demonstrated a lower rate of carbohydrate utilization in skeletal muscle after a fat than after a carbohydrate rich diet both at rest and during exercise. To test the hypothesis of citrate as a regulator of glycolysis (1) arterial‐femoral venous (a‐fv) differences for oxygen, citrate, pyruvate and lactate and (2) muscle citrate and glucose‐6‐phosphate (G‐6‐P) were determined at rest and after 5 and 25 min of submaximal bicycle exercise. Citrate release and muscle citrate concentration were higher after fat than after carbohydrate diet at rest and 5 min exercise, but did not differ between diets at 25 min exercise. Lactate release and muscle lactate concentration were lower after fat diet at 5 and 25 min exercise. Pyruvate release at 5 min exercise was higher after fat diet. The G‐6‐P concentration was higher at rest, insignificantly higher after 5 min exercise and lower at 25 min exercise after the fat diet. The findings support the notion that at rest and 5 min exercise fat diet induced inhibition of glycolysis might be mediated through increased intramuscular citrate acting on phosphofructokinase. In addition, the greater pyruvate release at 5 min exercise after fat diet in spite of a smaller lactate release, indicates a decreased pyruvate dehydrogenase activity and/or NADH to NAD ratio after fat diet. The inhibition of glycolysis at 25 min exercise after fat diet on the other hand does not seem to be c

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07492.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Plexuses of nerve fibres containing neuropeptide Y (NPY)‐like immunoreactivity invest pial arteries belonging to the circle of Willis, pial arterioles, occasionally penetrating arterioles and large veins. A more sparse supply of NPY‐like fibres are observed around pial veins and venules. The NPY‐immunoreactive fibres are located within the adventitia or at the adventitia‐media border. Only occasional fibres are present in cerebral vessels of animals in which the superior cervical ganglion has been removed one week previously. Administration of NPY resulted in strong, concentration‐dependent contractions of isolated feline middle cerebral arteries whereas administration of avian pancreatic polypeptide (APP) elicited weak contractions. In chloraloseanaesthetized cats, perivascular microapplication of NPYin situresulted in marked concentration‐dependent contractions of cerebral pial arterioles (34.7±6.6%; maximum decrease in calibre with NPY. Perivascular administration of NPY resulted in the constriction of pial veins but the magnitude of the venous calibre reductions was smaller than the response of arterioles at each reductions was smaller than the response of arterioles at each concentration examined. APP did not elicit contraction of pial arterioles or veins duringin situconditions. The pharmacological and immunocytochemical results strongly indicate the existence of a novel perivascular neuronal system containing NPY, which mediates contraction of cerebral blood vessels and NPY is colocalized with NA in sympat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07493.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In cat middle cerebral arteries (CMCA) preincubated with3H‐noradrenaline (NA), the outflow of tritium evoked by electrical stimulation was reduced to 32% by α‐adrenoceptor (α‐receptor) stimulation with oxymetazoline, and increased to 487% by α‐receptor blockade with HEAT. The relative order of potency for α‐receptor agonists on prejunctional receptors was: clonidine ≥ oxymetazoline>phenylephrine, and the antagonist rauwolscine was more potent than prazosin. This indicates that the prejunctional α‐receptors are mainly of α2‐type. Rauwolscine was more potent than prazosin in inhibiting the contractions induced by NA, indicating a predominance of α2‐receptors postjunctionally. Apart from clonidine having higher intrinsic activity pre‐ than postjunctionally, all drugs examined (oxymetazoline, phenylephrine, rauwolscine, HEAT (BE2254), and prazosin) had similar concentration‐effect curves on the pre‐ and postjunctional receptors. Furthermore, the ratios of EC50‐values pre‐ and postjunctionally of rauwolscine, oxymetazoline, and clonidine were all close to unity. These results indicate that pre‐ and postjunctional α2‐receptors in the CMCA have similar pharmacological characteristics and cannot be influenced

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07494.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The male rat urinary bladder belongs to those few structures where both the post‐ and preganglionic parasympathetic nerves are accessible for severance. In the present study the sensitivity to the parasympathomimetic drug methacholine of muscle strips of either denervated or decentralized bladders was examined in vitro. One week postoperatively denervated and decentralized bladders were sensitized to the same degree, the ED50values being 4 times less than ED50of unoperated control bladders. In contrast to the decentralized bladders the supersensitivity in the denervated ones was found to have increased further when tested four weeks postoperatively, the ED50value being about 20 times less than that of controls. The present findings are in agreement with Cannon's “law of denervation”. The results are discussed in relation to possible mechanisms behind the phenomenon of supersensit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07495.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Our previous investigations have indicated that β2‐adrenergic regulatory mechanisms contribute to important compensatory hemodynamic adjustments in hemorrhage. In the present study an attempt was made to examine, by comparative observations after standardized fatal hemorrhage on cats with intact and ‘selectively’ blocked β2‐adrenoceptors (ICI 118,551), whether such compensatory effects are crucial for survival. On the average, the survival time after bleeding was 686 min in cats with intact and 427 min in cats with blocked β2‐adrenoceptors (p<0.05), the difference thus approaching 4.5 h. It is suggested that the reduced survival time after β2‐blockade, at least partly, can be ascribed to interference with the circulatory β2‐adrenergic control in hemorrhage aimed at improvin

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07496.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY