摘要:

AbstractIn order to find out if there are age‐related changes in human skeletal muscle metabolism or ultrastructure, biopsy material from 56 sedentary men aged 22–65 years was studied by means of enzyme activity determinations, histochemistry and quantitative electron microscopy. For comparison, a younger (16–18 years) and an older (66–76 years) group were included. These subjects were relatively more active. There was an increase in percentage of slow twitch fibres with age. Mitochondrial volume fraction decreased with age, primarily due to diminished mean mitochondrial volume. In spite of this, no overall decrease in the activities of five enzymes, representative of the major pathways in energy metabolism, was observed. Thus, increased amounts of enzymes per unit mitochondrial volume are implicated. Lipofuscin was more frequently found in the older groups. Correlations were present between fibre type distribution and oxidative enzymes, as well as between different enzymes. It was concluded, that the decrease in maximal oxygen uptake and muscular strength in aging humans probably may not be explained in terms of a deteriorating skeletal muscle energy met

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06277.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractEnterochromaffin cells (EC) from the cat duodenum were studied before and after electrical efferent stimulation of the cervical vagal by means of electron microscopy and fluorescence histochemistry according to the Hillarp‐Falck technique. From the same animals portal blood plasma was assayed for serotonin (5‐HT) at various stages of the nerve stimulation. Within 15 min after the onset of vagal nerve stimulation there was a more than twofold increase of the portal 5‐HT levels, which returned to normal after cessation of stimulation. There was also a pronounced reduction in the fluorescence intensity of EC demonstrating a lowered intracellular 5‐HT level. Ultrastructurally there was evidence for basal exocytosis as well as for a release of osmiophilic material from the EC directly into the gut lumen after nerve stimulation. Together, these observations strongly suggest a vagally induced 5‐HT release from EC i

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06278.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe present study, which concerns the rate of changes in the cerebral cortex concentrations of phosphocreatine (PCr), ATP, ADP, AMP, lactate and pyruvate during complete ischemia, had the objective of finding out whether or not phenobarbital retards depletion of tissue energy reserves during ischemia. Ischemia was induced for periods of 10 s to 10 min in animals maintained on 70% N2O or given 150 mg. kg‐lof phenobarbital. The results showed that the barbiturate anaesthesia delayed utilization of ATP during the first 2 min. However, after 5 min of ischemia PCr and ATP concentrations, as well as the calculated adenylate energy charge, were identical in animals anaesthetized with nitrous oxide and phenobarbital. Thus, phenobarbital induces a very moderate delay in the depletion of cerebral energy reserves that occurs during complete ischemia. The results obtained after 5–20 s of ischemia allowed calculation of energy (˜P) utilization according to Lowryet al(1964). The closed system method gave values for Putilization which were not far from those obtained by CMRo, measurements. However, with normal values for metabolic rate (70% N2O) valid estimates are obtained only with very short ischemic periods (5–10 s) and, with such short periods, the oxygen content of the tissue may introduce an

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06279.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractStimulation of the sympathetic nerves to the brain is known to make the resistance vessels able to with stand a higher blood pressure,i.e. to prevent blood‐brain harrier (BBB) dysfunction and overpcrfusion in acute hypertension. When hypertension occurs concomitantly with a metabolic vasodilatatione.g. during epileptic seizures and after amphetamine‐administration, protein leakage in the brain is more pronounced than in hypertensionper se. Unilateral stimulation of the cervical sympathetic chain during the administration of amphetamine or bicuculline—the latter a GABA‐receptor blocking substance that induces epileptic activity—attenuated the leakage of Evans blue‐albumin and125IHSA into the brain. Our results thus indicate a prophylactic effect of sympathetic stimulation also when hypertension is combined with a nletabolically induced vasodilatation. The sympathetic nerves may constrict both extracerebral arteries and intracerebral resistance vessels. Unexpectedly the effect on the BBB of unilateral stimulation was to a great extent bi lateral under the present experimental

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06280.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe influence of estrogen treatment on3H‐noradrenaline release, induced by potassium or calcium, was studied in isolated preparations of the uterus and the portal vein of the rat. Uterine strips of oophorectomized rats responded with contraction followed by transient relaxation when immersed in a medium containing 127 mM potassium. The transient relaxation was accompanied by an increased rate of3H‐nor‐adrenaline efflux. When the uterine strips were bathed in calcium‐free potassium solution, addition of calcium (3 mM) evoked an increased outflow of3H‐noradrenaline coinciding with a relaxation phase of the contractile response to calcium. After estrogen treatment of the rats the pattern of response was altered. The uterus then responded to potassium and calcium with sustained contractures and with a relatively small (potassium) or with no (calcium) increase of3H‐noradrenaline efflux. Normetanephrine (5 × 10‐‐5M) did not influence the uptake or release of3H‐noradrenaline in either non‐estrogenized or estrogen treated rats uterus. Calculations, based on the amounts of3H‐noradrenaline released by potassium and on the inhibitory effects of desipramine (10‐‐5M) on neuronal uptake of noradrenaline, suggested that similar amounts of tracer were accumulated in the adrenergic nerves of both non‐estrogenized and estrogen treated preparations. Tyramine (10‐‐4M) had a weaker stirnulatory effect on3H‐noradrenaline release than potassium, and the tyramine induced release was not inhibited by estrogen treatment. Strips of the rat portal vein responded to potassium with an increased rate of3H‐noradrenaline efflux. As in the uterus, estrogen treatment reduced the release of3H‐noradrenaline in response to potassium. The adrenolytic effect of estrogen is possibly due to reduced entry o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06281.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBy using a radially directed stream of fluid it is possible to compress a section of a nervein vitroby known pressures without interrupting the supply of oxygen and nutrients to the nerve. Motor neurons of the vagus nerves of rabbits labelled withSH‐leucine were used at room temperature. When a nerve was subjected to 20 mmHg pressure fast axoplasmic flow was not altered, but at 30 mmHg there was a slight but consistent inhibition, which was even more marked at 60 mmHg and still more at 90 mmHg. The pressure induced block of axoplasmic flow was reversible when 60 mmHg pressure was applied for as long as 4 h, when the nerves were compressed for 15 h there was reversibilkty in only 5 out of 8 case

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06282.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractEffects of moderate hemorrhage were studied in normovolemic and hydrated conscious goats. Plasma arginine vasopressin (AVP) in jugular vein blood did not rise in response to bleeding of 8 and 12 ml/kg b.wt. After a blood loss of 16 ml/kg an abrupt and conspicuous rise in plasma AVP (to>10 times basic level) was seen in 50% of the experiments, whereas no rise in AVP occurred in the remaining experiments. Bleeding at 20 and 24 ml/kg gave a more consistent AVP response. Hydration did apparently not reduce the AVP‐responsiveness to bleeding. The plasma vasopressin concentration returned to pre‐hemorrhage level about 3 h after bleeding,i.e. before the blood was re‐transfused. A minor, and inconsistent rise in plasma renin activity occurred in response to bleeding. Central venous pressure fell during hemorrhage and stayed depressed until the blood was re‐transfused. Since the depression was of the same order in all experiments, and was still present when plasma AVP had returned to pre‐hemorrhage level, the fall in venous pressure was obviously not the main cause of the AVP‐response. However, the pronounced riseinplasma vasopressin was correlated to a fall in the arterial pressure and to hyperventilation. No urge to drink developed during any of the hemorrhage experiments. It is concluded that the goat does not readily respond to hemorrhage with vasopressin liberation. When it happens, pressor amounts of the hormone are released, and a fall in arterial pressure and/or increased stimulation of respiratory chemoreceptors (hypoxia?) appear(s) to be the ultimate cause(s) of the release. This thirst‐independent regulation of vasopressin secretion is obviously of no importance in day to day control of water balance, but may help to maintain the arterial blood pressure in emergen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06283.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe diffusion exchange of Cr‐EDTA, using the single injection indicator diffusion method, was followed simultaneously with estimations of the capillary filtration capacity (CFC) in an “isogravimetric” rat hindquarter preparation during artificial perfusion and maximal dilatation. Measurements were performed at constant flow and during 1) shifts in filtration‐absorbtion, 2) alterations of perfused capillary wall area (graded rarification of capillary network by microsphere injection) and 3) during alterations of permeability (i.a. infusion of histamine). At maximal vasodilatation CFC was 0.037 ± 0.001 ml/min × mmHg × 100 g and PS for Cr‐EDTA 5.67 ± 0.13 ml/min × 100 g. During filtration or absorbtion, Cr‐EDTA transfer from vessels to interstitium changed only slightly but the situation may well be different for solute transfer from interstitium to vessels. Alterations in capillary wall area resulted in proportional changes in PS for Cr‐EDTA while the CFC changes were always relatively smaller. Histamine increased CFC some threefold with a marked increase in protein transfer, while PS for Cr‐EDTA increased only marginally. This hista mine effect could be ascribed mainly to an increase in the number of large pores which, because of their relative paucity, are of little importance for small molecular diffusion exchange but highly important for convective and mac

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06284.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe β‐oxidation of palmitate, palmitoyl‐CoA and palmitoyl‐L‐carnitine proceeded at a high rate in isolated rat liver mitochondria. At high concentrations (100 nmol/mg protein) the oxidation of palmitate and palmi‐toyl‐CoA was only partly carnitine dependent. All substrates were most rapidly oxidized in the presence of oxaloacetate and state 3 conditions. Succinate inhibited β‐oxidation especially in state 4 conditions. β‐Oxidation was faster in hypotonic than in isotonic medium both in state 3 and state 4 conditions. Hyper‐tonicity inhibited β‐oxidation. The initial formation of palmitoyl‐CoA from palmitate, CoA and ATP was faster than the oxidation of palmitate under identical conditions. The presence of bovine serum albumin inhibited the β‐oxidation, especially with palmitoyl‐CoA or free palmitate as the substrates. Mitochondria contain a palmitoyl‐CoA hydrolase which may influence the available intramitochondrial palmitoyl‐CoA. The present results demonstrate no single rate limiting step in the β‐oxidationin vitro. Both the NADH/ NAD ratio, competition for the respiratory chain, the level of ADP, binding of palmitoyl‐CoA to extramitochondrial protein, and possibly intramitochondrial hydrolysis of palmitoyl‐CoA all seem to influence the rate of β‐oxidationin vitro. It is suggested thatin vivothe most important factor is the availability of acyl‐CoA to the outer carni

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06285.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe vasomotor response of dopamine and dopaminergic agonists was studiedin vitroon middle cerebral arteries from cat and pial arteries from humans. The action of various inhibitors was tested in order to define the receptors involved. A contractile response could be obtained by epinine, apomorphine and dopamine in the mentioned order of potency. The effect was blocked byalpha‐receptor as well as serotonin receptor antagonists. The mode of inhibition suggested that serotonin receptors rather thanalpha‐adrenoceptors mediated the dopamine‐induced contraction. A dose‐dependent dilatation could be evoked by the dopaminergic agonists on actively contracted pial arteries. The relative potency was epinine>dopamine>apomorphine. The order of potency for the agonists, together with blocking experiments (including a parallel shift in the log dose‐response curve induced by bulbocapnine), indicated that the vasodilatation is mediated by specific dopamine

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06286.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY