摘要:

The effect of 2 and 4 h of tourniquet ischaemia followed by 1 h of reperfusion on the major mitochondrial phospholipids and on the cytochrome c oxidase kinetic parameters has been investigated in rat skeletal muscle. There was no change either in the mitochondrial phospholipid content or in theVmaxand theKmof the enzyme after 2 h of ischaemia with and without subsequent reperfusion. Four hours of ischaemia had no effect on the lecithin and the cephalin content, while the cardiolipin content decreased as well as theVmaxof the enzyme (P<0.05). Tissue reperfusion caused a dramatic decrease in both cardiolipin (55% of the control,P<0.001) andVmax(38% of the control,P<0.001). The corresponding reduction in lecithin and cephalin contents was 12% and 14% respectively (P<0.05). TheKmremained unchanged at all conditions. These findings suggest that mitochondrial dysfunction in response to ischaemia and reperfusion could be a consequence of the reperfusion itself following severe ischaemia. The results are discussed in terms of cardiolipin peroxidation and cytochrome oxidase as a functional parameter.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08822.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Creatine kinase (CK) release from male and female rat soleus muscles was studied for 4.5 hin vitro, under basal conditions and after electrical stimulation. Basal CK release was greater from male than from female muscles, and CK release from male muscles increased significantly when the muscle tension in thein‐vitroset‐up was increased. CK release after electrical stimulation was also more marked in male soleus muscles. Pretreatment of male rats and ovariectomized female rats with oestradiol for 3 weeks attenuated the enzyme efflux, but ovariectomy 24 h before in females, or oestradiol administration 24 h before in males, did not affect the release of CKin vitro.The data show that sex‐linked differences in CK efflux are still present, under both basal and stimulated conditions, when muscles are isolated from the intact animal, and that hormone treatment of the intact animal affects these properties in the isolated musclein vitro.(Experiments with rats were performed under supervision of a legally appointed administr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08823.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In a previous study, prolonged low‐frequency muscle stimulation in the hind leg of the fully conscious spontaneously hypertensive rat (SHR) was shown to induce a long‐lasting reduction of blood pressure. It was also shown that opioid and serotonergic (5‐HT) systems were involved. More recently, we have shown that the 5‐HT1receptors are involved in the post‐stimulatory decrease in blood pressure.In the present study, the influence of this type of muscle stimulation on the pain threshold was investigated. Pain perception was measured as the squeak threshold to noxious electric pulses. After cessation of the stimulation, an analgesic response was elicited within 60 min and peak analgesia developed after 120 min, being 139 ±10% (P<0.01) of the prestimulatory control value. The increased pain threshold lasted for another 2 h.One group of SHR was pretreated with PCPA, a serotonin synthesis blocker, which completely abolished the post‐stimulatory analgesia. To analyse further the involvement of different serotonin systems, drugs with selective affinity for 5‐HT receptors were used. In one group a prestimulatory dose of metitepine maleate (a 5‐HT1&2receptor antagonist) abolished the post‐stimulatory elevation of the pain threshold. The prolonged analgesic response was still present after prestimulatory treatment with ritanserin or ICS 205–930 (5‐HT2and 5‐HT3blocking agents respectively).In another group of experiments, the serotonin receptor antagonists were administered post‐stimulation to animals with fully elicited analgesia. None of the antagonists used could reverse the elevation of pain threshold towards prestimulatory levels.Thus, intact 5‐HT systems were necessary to elicit the analgesia to muscle stimulation and the response was mediated by the 5‐HT1receptor. However, the results indicate that serotonin is not required to maintain the analg

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08824.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The differences in cardiorespiratory responses were examined during and after intermittent progressive maximal arm‐crank and cycle exercise. Arm‐crank exercise was performed in a standing position using no torso restraints to maximize the amount of active skeletal muscle mass. Recovery was followed for 16 min. In the tests a variety of ventilatory gas exchange variables, heart rate, the blood pressure, and the arm venous blood lactate concentration were measured in 21 untrained healthy men aged 24–45 years. At equal submaximal external workloads for arm cranking and cycling (50 and 100 W) the respiratory frequency, tidal volume, pulmonary ventilation, oxygen uptake, carbon dioxide output, the respiratory exchange ratio, heart rate, the arm venous blood lactate concentration, and the ventilatory equivalent for oxygen were higher (P<0.001) during arm cranking than cycling. The maximal workload for arm cranking was 44% lower than that for cycling (155 ±37vs277 ± 39 W,P<0.001) associated with significantly (P<0.001) lower maximal tidal volume (‐20 %), oxygen uptake (‐22 %), carbon dioxide output (‐28%), systolic blood pressure (‐17%) and oxygen pulse (‐22%) but a higher ventilatory equivalent for carbon dioxide (+ 22%) and arm venous blood lactate concentration (+ 37%). However, these responses after arm‐crank and cycle exercises behaved almost similarly during recovery. The high cardiorespiratory stress induced by arm work should be taken into account when the work stress and work‐rest regimens in actual manual tasks are assessed, and when arm work is used for clinical testing, and in physiotherapy particularly for patients with heart

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08825.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Our objective was to assess the importance of arterial baroreflexes in maintaining vasoconstriction in active muscle during moderate to severe exercise. Eight subjects exercised for 8–15 min on a cycle ergometer at three levels (averages 94, 194, 261 W) requiring 40–88 % ofVo2max. Four times during each exercise level pulsatile negative pressure (– 50 mmHg) was applied over the carotid sinuses for 30 s; suction was applied at each ECG R‐wave for 250–400 ms. Before and during each neck suction, femoral venous blood flow (FVBF) was measured by constant infusion thermal dilution. At 94 W neck suction significantly reduced blood pressure (BP) (15 mmHg) and heart rate (HR) (7 beats min‐1), and raised leg vascular conductance (LVC) (11.4%) without changing FVBF. At 194 W, neck suction reduced BP (9 mmHg), HR (4 beats min‐1) and FVBF (5.1%, 240 ml min‐1), and raised LVC (5.2%). At 261 W, LVC was unchanged by neck suction, but BP and FVBF both fell (9 mmHg and 650 ml min‐1or 7.4%). We conclude that competing local vasodilation and sympathetic vasoconstriction control muscle blood flow during moderate exercise, and vasoconstrictor tone can be withdrawn by baroreceptor stimulation. High levels of vasoconstrictor outflow to muscle in severe exercise may not originate

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08826.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effect of intracerebroventricular (i. e. v.) infusion (0.02 ml min‐1) of deuterium oxide (D2O), with NaCl added to isotonicity, on the water intake and arginine vasopressin (AVP) release caused by intravenous (i. v.) infusion of angiotensin II (All) (4.8 nmol min1) was studied in euhydrated sheep. The i. e.v. infusion of D2O, which started 80 min before commencement of the All infusion, induced a water diuresis in four out of six animals and a measurable decrease in plasma AVP concentration. The i. v. infusion of All effectively stimulated the AVP release and the response was unaffected by prior and simultaneous i. c.v. administration of D2O. However, the water intake measured 2 min after cessation of the All administration was reduced by 50% when D2O was infused i. c.v. compared to that seen after simply the All infusion. The inhibitory effect of D2O on All‐induced drinking disappeared rapidly after discontinuation of D2O administration. Compensatory increased drinking was seen during the first post‐infusion hour, resulting in an equivalent cumulative intake of water at 60 min post‐infusion in the two types of experiments. The present results support the idea that at least some of the cerebral effects of circulating All on fluid balance are medicated via targets which are simultaneously accessible to influences from the blood and the cerebrospina

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08827.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The reduction in blood pressure due to ANF(103–126) fails to elicit reflex cardioacceleration in the conscious rat. To examine baroreflex sensitivity, the effect of ANF(103–126) on the heart period (HP) response to rapid central volume expansion and to alterations in mean arterial pressure (MAP) induced by bolus injections of phenylephrine and sodium nitroprusside was assessed. ANF(103–126) significantly augmented the bradycardic response induced by acute volume expansion from 426 ± 21 to 391 ± 23 beats min‐1versus 421 ± 23 to 405 ± 24 without ANF(103–126). Baroreflex sensitivity was defined by the ratio of the change in heart period to the maximal change in mean arterial pressure. The dose of ANF(103–126) utilized did not affect basal heart rate or the magnitude of the mean arterial pressure response to phenylephrine but did significantly enhance the nitroprusside‐induced decrease in mean arterial pressure. Baroreceptor sensitivity to phenylephrine was significantly increased by ANF(103–126): 0.997 ± 0.07 (ms mmHg‐1) during ANF(103–126)vs0.613 ± 0.08 during vehicle. The total duration of the heart rate response to phenylephrine was also prolonged. In contrast, ANF(103–126) did not alter the baroreceptor sensitivity (1.45 ± 0.3vs1.43 ± 0.2 ms mmHg‐1) or duration of heart rate response to nitroprusside. In the conscious rat, ANF(103–126) modifies the heart rate response to changes in mean arterial pressure and acute central volume expansion. This action appears to be dependent on stimu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08828.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Heart rate (HR), mean arterial pressure (MAP), indices of sympathetic and parasympathetic activity (plasma concentrations of adrenaline, noradrenaline and pancreatic polypeptide, PP), vasopressin (VP) and aldosterone (ALDO) were measured in six pigs during continuous bleeding resulting in hypovolaemic shock, from which five survived. Three stages of haemorrhage could be defined.Stage I.Resting MAP was 85 ± 6 mmHg and increased to 96 ± 5 mmHg with a blood loss of 275 (range 250–300) (10 (9–12)% of the estimated blood volume) concomitant with an increase in HR from 105 ± 5 to 113 ± 6 beats min‐1(P<0.05).Stage II.After a blood loss of 375 (300–500) ml (15 (13–16)%) MAP fell to 62 ± 9 mmHg and HR to 95 ± 5 beats min‐1(P<0.05).Stage III.A blood loss of 1113 (825–1450) ml (44 (30–52)%) resulted in a MAP of 50 ± 4 mmHg and an increase in HR to 206 ± 3 beats min‐1(P<0.05). Adrenaline increased from 0.3 ± 0.1 to 0.8 ± 0.3 (stage II) and 3.6 ± 1.1 nmol l‐1(stage III) (P<0.05); noradrenaline from 0.4 ± 0.1 to 1.5 ± 0.4 (stage II) and 5.9 ± 1.7 nmol l‐1(stage III) (P<0.05); PP from 6.2 ± 1.6 to 13.3 ± 2.3 (stage II) and 20.9 ± 7.8 pmol l‐1(stage III) (P<0.05). VP changed only marginally, but ALDO increased from 496 ± 54 to 623 ± 76 pmol l‐1(stage III) (P<0.05). The results suggest that a high HR and intense sympathetic activity is seen during severe haemorrhage in the pig while vagal slowing of the heart and moderate hypotension are prominent when bleeding amounts to app

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08829.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Gastrin releasing peptide (GRP) is an intrapancreatic peptide, but its physiological function is unknown. Previously, the peptide has been shown to increase plasma levels of insulin and glucagonin vivoin dogs, but no studies on the possible direct actions on islet hormone secretion from the dog pancreas have been undertaken. Therefore, we examined the effects of a 10‐min perfusion of synthetic porcine GRP at four different dose rates over a wide range (0.1–50 nmol l‐1) on the islet hormone release from the isolated dog pancreas (n= 5–6 in each group) at 5.5 mM glucose. We found that, at all four concentrations tested, GRP rapidly and markedly stimulated insulin secretion. The stimulation was, however, transient: the increased insulin secretion returned to basal levels within 7–8 min despite the ongoing GRP perfusion for 10 min. In contrast, GRP did not affect the pancreatic secretion of glucagon or somatostatin. We conclude that GRP stimulates insulin secretion by a direct pancreatic action without affecting the secretion of glucagon or som

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08830.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Experiments were performed on acutely vagotomized cats during chloralose anaesthesia. In order to avoid sympathoadrenergic influences, the adrenal glands were ligated and the splanchnic nerves were cut bilaterally in all animals. The gastric lumen was perfused with saline and the H+secretion was calculated from pH measurements in the perfusate. HCO3‐secretion by the duodenal mucosa was titratedin situ.Omeprazole (4 mg kg‐1i. v., dissolved in PEG400, 40% w/v) did not influence basal or vagally induced HCO3‐secretions, but inhibited by about 80% the H+secretory response induced by electric vagal stimulation. Acute administration of ranitidine (5 mg kg‐1i. v.) transiently lowered arterial pressure, an effect which was followed by a sustained compensatory tachycardia. Ranitidine raised basal duodenal HCO3‐secretion by 50% and inhibited vagally induced gastric H+secretion by about 70%, whereas vagally induced HCO3‐secretion was not influenced. The results suggest that vagal nerve stimulation raises the duodenal bicarbonate secretion via a mechanism independent of the level of gastric

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08831.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY