摘要:

Endomyocardial biopsies were taken from the apex of the left ventricle in 15 patients operated on for aortic valve disease or ischaemic heart disease and from papillary muscles in six patients operated on for mitral valve disease. Activities of cardiac phosphofructokinase (PFK), total lactate dehydrogenase (LD), its isoenzyme LDDaspartate aminotransferase (ASAT), total creatine kinase (CK), its isoenzyme MB, citrate synthase (CS) and myoglobin content (MYO) were related to the angiographically determined left ventricular function. Activities of total LD, PFK and PFK/CS ratio were lower in patients with decreased, than in those with normal, left ventricular function. Myoglobin content and activities of CS and ASAT were not related to left ventricular function. It is suggested that depressed left ventricular contractility is associated with a decreased glycolytic capacity while the oxidative capacity is mainly unaltered.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08329.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The aim of the study was to test the hypothesis that baroreceptor unloading increases jejunal fluid absorption rate via an α2‐adrenergic effect on electrogenic active transport. In 13 chloralose‐anaesthetized cats, the carotid sinus baroreceptors were isolated and perfused with arterial blood, and we studied the effects of a graded decrease in carotid sinus pressure on intestinal vascular resistance, net fluid absorption rate and the potential difference between the intestinal lumen and the peritoneal cavity (PD). Experiments were performed in seven control animals and in six animals pretreated with yohimbine, an α2‐adrenergic antagonist, at a dose of 0.1 mg kg‐Ii.v. Yohimbineper sehad no significant effects on systemic arterial pressure, intestinal vascular resistance, net fluid absorption rate or PD. In the control animals, baroreceptor unloading induced an increase in systemic arterial pressure, intestinal vascular resistance and net fluid absorption rate, and a decrease in the PD. Yohimbine pretreatment did not significantly affect the systemic blood pressure response to baroreceptor unloading, but abolished the effect on intestinal vascular resistance and PD. After yohimbine treatment, decreases in carotid sinus pressure still enhanced net fluid absorption rate, but this response was observed in a higher range of carotid sinus pressures than in control animals. We conclude that (1) a major component of the increase in jejunal absorption rate during baroreceptor unloading is due to a non‐electrogenic mechanism, which may be either active or passive; (2) this component of the response is not blocked by yohimbine at a dose sufficient for an effect on presynaptic α2‐receptors; (3) the absorptive response to baroreceptor unloading is not a phenomenon secondary to the concomitant jejunal va

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08330.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The present study was conducted to examine the mechanisms behind the previously reported beneficial effects of high doses of naloxone on impaired cerebral function due to hypotensive haemorrhage in spontaneously hypertensive rats (SHR). The stereo‐specificity of the effects of two opioid receptor antagonists, naloxone (Nal) and Win 44.441‐3 (Win), was tested. The effects of thyrotropin releasing hormone (TRH) were also examined, because this peptide has been shown to have beneficial effects in neuronal ischaemia due to spinal injury. In addition, we were interested in seeing what effect the GABA antagonist, bicucculine (Bic), had on cerebral function during relative ischaemia, because Nal in high doses is suspected to antagonize GABA transmission. Mean arterial pressure (MAP), heart rate (HR) and somatosensory evoked potentials (SEP) were recorded in chloralose‐anaesthetized SHR. The rats were bled and MAP was rapidly lowered to 50 mmHg. This resulted in transient bradycardia and attenuated SEP. When the first SEP component had decreased to 40–50% of control, the animals were retransfused to a MAP of 60–80 mmHg, to prevent further deterioration of SEP, and maintained at the new pressure level for the rest of the experiment. Fifteen to twenty minutes later, Nal, Win, TRH or Bic was injected i.v. Both (–)Nal (5 mg kg‐1) and (–)Win (imgkg‐1) improved SEP in a stereospecific manner. (+)Naloxone or (+)Win did not affect SEP significantly. Thyrotrophin releasing hormone (2 mg kg‐1) caused further attenuation of a late SEP component. The effects of Bic (0.15‐0.25 mg kg‐1) varied between animals but, on average, no significant effects were observed. Thus, the results strongly indicate the involvement of endogenous opioids in the pathophysiology of cerebral ischaemia and indicate beneficial effects of opioid receptor antagonists on cerebral function in this model of rela

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08331.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A possible role for Ca2+in the α‐adrenoceptor‐induced inhibition of glucose‐stimulated insulin secretion was studied in isolated rat islets by the use of the selective α2‐adrenoceptor agonist clonidine. We found that clonidine, in contrast to the a,‐adrenoceptor agonist phenylephrine, inhibited glucose‐stimulated insulin secretion at dose levels below 10‐6mol l‐1. In islets preloaded with46Ca2+and perifused at 2 mmol llCa2+, clonidine (10‐6moll‐1) reduced the glucose (13.3 mmol l‐1)‐stimulated46Ca2+efflux during both the first and second phases of insulin secretion. Furthermore, the inhibitory effect of clonidine on glucose (13.3 mmol l‐1)‐stimulated insulin secretion was partially counteracted by raising the extracellular Ca2+concentrations. Moreover, the calcium channel agonist Bay K 8644 counteracted the inhibition by clonidine on glucose‐stimulated insulin secretion. Our results suggest that selective α2‐adrenoceptor‐induced inhibition of glucose‐stimulated insulin secretion is mediated, at least partially, by restraint of Ca2+‐influx. This action might in turn be exerted through interference wit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08332.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

On superfusion of chromaffin granules from bovine adrenals with isotonic sodium and potassium salts, catecholamines and ATP were released in parallel and both in accordance with ion exchange kinetics. An artificial model was prepared by mixing a cationic (IRC‐50) and an anionic (IR‐4B) ion exchanger with COO and NH+3groups, respectively, as binding sites. This mixed ion exchanger showed in its storage and release of CA+and ATP‐striking similarities to the chromaffin granules. Within the pH range given for the interior of the granules ‐ 5.5–6 ‐ the artificial model even stored and released CA+and ATP‐within the same molar ratio as observed for the granules. We hypothesize that the chromaffin granule matrix in its storage and release functions operates as an amphoteric ion exchanger with COO‐and NH+3, groups as th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08333.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Low levels of thioredoxin and thioredoxin reductase immunoreactivity were demonstrated immunohistochemically in rat gastric epithelial cells. The intensity was influenced by feeding and fasting, the former resulting in diminished reactions. Acute vagotomy, which abolishes basal acid secretion, resulted in a strongly increased thioredoxin immunoreactivity in all gastric epithelial cells. Stimulation of vagotomized rats with pentagastrin and carbachol reduced the levels of thioredoxin and thioredoxin reductase. Atropine and omeprazole (in stimulated, vagotomized rats) completely inhibited acid secretion, but caused different effects on the thioredoxin levels of gastric cells. Atropine restored the thioredoxin immunoreactivity in most gastric epithelial cells to that of the unstimulated, vagotomized controls. Omeprazole, however, did not reverse the effects of stimulation, and, except in the parietal cells, weaker fluorescence was observed. Similar reaction patterns were seen for thioredoxin reductase, although at lower staining intensities. The results demonstrate that thioredoxin and thioredoxin reductase are expressed in resting cells, and to a lower extent in cells with ongoing secretion.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08334.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In order to evaluate the role of the pineal gland in human reproduction, day‐ and nighttime concentrations of serum melatonin, FSH, LH and prolactin were measured by radioimmunoassays on various days of the menstrual cycle during summer (average daylight 22 h) and winter (daylight 5 h) in healthy females (n= 12) from northern Finland (65oN). A multifactorial analysis of variance showed that, in addition to the well‐established increases of gonadotropins at midcycle and melatonin and prolactin at night, there was a significant effect of season on the serum levels of melatonin and LH. Night‐time serum melatonin levels on cycle days 2 and 10 were 27% and 49% (P<0.05 and<0.01) higher in winter than in summer. Night‐time serum LH levels at midcycle were 76% (P<0.05) higher in summer than in winter. There were no significant effects of season on the serum levels of FSH, prolactin, day‐time melatonin or LH outside the mid‐cycle. Neither were there any significant effects of the day of the menstrual cycle on the serum melatonin levels. It is possible that in winter the high levels of melatonin in the follicular phase have an inhibitory effect on the serum LH levels. In summer the melatonin levels are lower and perhaps less inhibitory on the secretion of LH, resulting in the stimulation of the reproductive competence in hu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08335.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Uterine and ovarian blood flows and ovarian fractional perfusion were measured in adult rats anaesthetized with sodium pentobarbital i.p. on day 6 of pseudopregnancy, by using radioactive microspheres. Fifty i.u. human chorionic gonadotropin (hCG) was found to increase the fractional perfusion of the ovary, and this was at least partially accomplished at the expense of the uterine blood flow, since this was reduced. Noradrenaline (NA) infusion (2 nmol min‐1) reduced ovarian as well as uterine blood flow acutely. After 20 min of NA infusion (2 nmol min‐1), however, ovarian blood flow and fractional perfusion were increased, while no significant effect was seen for uterine blood flow. Antidiuretic hormone (ADH) in a 20‐min infusion (1 nmol min‐1) markedly reduced ovarian and uterine bloo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08336.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Blood platelets from women showed increased sensitivity to adenosine diphosphate (ADP) during ovulation compared with menstruation. The increased sensitivity was registered as an increase in cytoplasmic calcium response measured with the fluorescent indicator fura‐2. Agonist dose‐response studies revealed an increased maximal response, but the dose that gave half maximal response was unchanged. This indicates an increased mobility of calcium, without changed affinity to receptor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08337.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The consequences of fibre heterogeneity on the collective force‐velocity properties of bundles of parallel fibres were examined in a simulation model. The model was tested by comparing the actual force‐velocity curve of a bundle of three fibres, each of which had been individually characterized, with the force‐velocity curve predicted by the model for the bundle based on the individual fibre properties. The predicted and measured force‐velocity curves were in excellent agreement. The curvature of the force‐velocity relation for a muscle, as indicated bya/P0in Hill's (1938) hyperbolic equation, increases with increasing heterogeneity in the maximum shortening velocities (Vmax(1)) of the individual fibres in the muscle. In a muscle that is heterogeneous with respect toVmax(1), the maximum shortening velocity determined by the slack test method (Vo) can be expected to represent the fastest fibre(s) in the muscle. The maximum velocity of shortening (Vm), determined by extrapolation from a hyperbola that is fitted to force‐velocity data at finite loads, is substantially lower thanVo.The difference in estimates ofVoandVmis a function of: (i) the degree of heterogeneity of the muscle with respect toVmax(1)and the curvature of the force‐velocity relationship of the individual fibres, and (ii) the force range used to establish the hyperbola from whichVmis derived. The ratio ofVmtoVOcan be used as an index to estimate the degree of variability in the maximum velocity of shortening among individual fibre

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08338.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY