摘要:

AbstractThe aim of the study was to investigate the influence of age on endurance of human skeletal muscle. An attempt was made to correlate muscular performance at various ages with some morphological and enzymatic characteristics of the muscle. Fifty healthy men, 22–65 years of age, with low daily physical activity (clerks) volunteered for the study. Isometric and dynamic endurance were determined under standardized conditions and measured in relation to maximum strength, thereby correcting for individual as well as age differences in maximum strength. Biopsies taken from the quadriceps muscle were used for muscle fibre classification, fibre area determinations, and measurements of some enzyme activities (Mg2+‐ stimulated ATPase, myokinase (MK), lactate dehydrogenase (LDH), LDH isozymes). Maximum isometric and dynamic strength decreased in the older groups while no significant change was seen in isometric or dynamic endurance. Significant correlations were observed between endurance and fibre type distribution, fibre areas, and LDH isozyme activit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06259.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractEarlier investigations have shown that the transport of aromatic amino acids into cerebral cortex slices of rats changes during ontogenetic development. In order to illuminate the possible influence of the developmental alterations of energy metabolism in the brain on the changes of the amino acid transport the influx of phenylalanine into cerebral cortex slices of adult and 7‐day‐old rats was measured in the presence of metabolic inhibitors. Also the levels of lactate, ATP, ADP, AMP and creatine phosphate in the slices were measured. The used inhibitors cyanide, dinitrophenol and iodoacetate, which disturb certain steps of energy metabolism, had very similar effects in both age groups on phenylalanine influx and on the levels of energy‐rich phosphates. The correlation between the level of ATP and the influx of phenylalanine was positive in both age groups, but the slopes of the regression lines were different. If ATP supplies energy for amino acid transport, its utilization, rather than its availability is a limiting factor in the slices from 7‐day‐old rats. Developmental changes in energy metabolism seem to have a minimal role in the changes of amino acid transport during the maturation of the brain. Changes in the properties of cell membrdne carriers and in the transmembrane ionic gradients may be more

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06260.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHepatic fatty acid biosynthesis and the activity of phosphatidate phosphohydrolase, the rate‐limiting enzyme of triacylglycerol biosynthesis, were studied after hypoxic periods of 1 and 7 days under hypo‐bark conditions at 40.8 kPa. Phosphatidate phosphohydrolase activity increased 2‐fold in the soluble fraction of the liver after one day at 40.8 kPa, but had returned to normal by 7 days. This was accompanied by a significant increase in liver triacylglycerol and sn‐glycerol‐3‐phosphate. The phosphatidate phosphohydrolase activity increased continuously over 7 days in the pair‐fed controls, probably due to the restriction on food. Measured asin vivoincorporation of3H2O into lipids, the hepatic fatty acid synthesis rate increased somewhat in acute hypoxia, but returned to normal values during 7 days of hypoxia. Plasma free fatty acids increased markedly after 24 h in the fasting controls (90 %) with a smaller increase in the hypoxic group (50%) due to peripheral lipolysis. Hepatic glycogen stores decreased in the hypoxic and fasting animals both after 1 and 7 days. It Is concluded that hypoxia induces the accumulation of fat into the liver at least partly as a consequence of an increase in phosphatidate phosphohydrolase activity in the soluble fraction

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06261.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe two mitotic inhibitors colchicine (COL) and podofyllotoxin (POD) and their respective isomers, IumiCOL and picropodofyllin (picPOD) were tested for their effect on the intraaxonal transport (AXT) of acetylcholine (ACh) and the cholinergic enzymes in rat sciatic nerve. The mitotic inhibitors and their isomers were dissolved in saline + 10%, ethanol (COL and lumiCOL) or dimethylformamid (DMFA) (POD and picPOD) and injected (3–5 γl) subepineurally into the sciatic nerve. As controls the vehicle (saline+ 10% ethanol or DMFA) alone were injected into some rats. 2 h later a crush operation was performed 15 mm distal to the site of injection. The accumulation of ACh or the two enzymes, ACh‐esterase (AChE) and cholineacetyltransferase (CAT), in the nerve segment proximal to the crush (12 h before death) was used as a measure of the AXT. COL and POD were very effective in inhibiting AXT of all 3 substances, while their isomers, lumiCOL and picPOD, were essentially without effect on AXT in equimolar concentrations (0.1 M). The effects on AXT of the 4 test substances thus appear related to their affinity to bind to tubulin, which is several orders of magnitude higher for COL and POD than for their isomers. The results further support the view that intact microtubules are essential for AXT of both membrane‐bound (AChE) and soluble (CAT) enzymes, as well as of ACh in rat motor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06262.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractInitial effects of pentobarbital (8 mg/kg) on autonomic efferent and afferent discharge rates were studied in 26 dogs under morphine‐chloralose anesthesia. Half of the dogs were given endotoxinE. coli(1 mg/kg) before pentobarbital. The postganglionic cervical vagal efferentation of all the dogs decreased as did the postganglionic cardiac sympathetic efferentation. The heart rate of the dogs given endotoxin decreased, while an increase in heart rate with abolition of respiratory arrhythmia, was observed in dogs without endotoxin. The aortic pressure of the former dogs dropped while it fell only slightly in the latter ones. The aortic arch baroreceptor activity decreased while the changes of left atrial B‐type receptor activity were not significant. The changes of the left atrial and central venous pressures were slight hut thosc of the pulmonary arterial pressure generally paralleled the changes in the aortic pressure. Pentobarbital, accordingly, seems to exert both sympatholytic and vagolytic effects. These explain the heart rate changes, as well as the impaired cardiac contractility it evokes. The obvious impairment of cardiovascular control mechanisms by pentobarbital should be seriously considered in investigations into the cardiovascular cont

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06263.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSpecimens of several rat tissues were purified with methanol extraction, gel filtration and cation exchange chromatography and measured for thyrotropin‐releasing factor (TRF) concentration by radioimmuno‐assay. TRF immunoreactivity of neural tissues (hypothalamus, spinal cord, medulla, cerebrum and cerebellum) and gastrointestinal tissues (pancreas, stomach, duodenum and colon) behaved as synthetic TRF during the purification. This dual distribution suggests that TRF‐secreting cells have their origin in the embryonal neuroect

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06264.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of ethanol intoxication and hangover on immunoreactive plasma arginine vasopressin (AVP) concentration was studied in 7 healthy supine men in controlled clinical conditions. In 6 subjects plasma AVP increased above control values at the time of maximal blood ethanol Concentration. The highest AVP values were observed in the subjects having nausea and vomiting and the worst hangover symptoms. During hangover plasma AVP values were higher than the controls and the response of plasma AVP to upright posture was exaggerated. The dissociation of plasma AVP concentration and ethanol diuresis suggested that the suppression of AVP release is not the sole determinant of ethanol diuresis. The study may indicate that the toxic effects of ethanol and the severity of hangover symptoms are associated with the state of hydration and individual sensitivity of AVP triggering mechanisms.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06265.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effects of unloading of the carotid baroreceptors on arterial plasma glucose concentration as well as on portal plasma immunoreactive glucagon (IRG) and insulin (IRI) concentrations were studied in an‐estethized, vagotomized cats either by sectioning the sinus nerves or by lowering the pressure in the isolated carotid sinuses. Complete elimination of the carotid baroreceptor discharge by cutting the sinus nerves caused an increase in the arterial plasma glucose concentration by 100% and an increase in the portal IRG level by about 200%, whereas the portal IRI concentration decreased to 50% of its basal value. These baroreceptor‐induced changes of the plasma IRG and IRI levels seemed to be graded in relation to the drop in carotid blood pressure and they were clearly detectable when the pressure was lowered from 120 to 90 mmHg in the isolated carotid sinus preparation. The described reflex hyperglycemia, hyperglucago‐nemia and hypoinsulinemia were mediated to the pancreas and liver mainly by the sympatho‐adrenal system, since cutting the splanchnic nerves above the adrenal glands abolished the hyperglycemic and hypoinsulinemic responses and markedly depressed the magnitude of the hyperglucagonemic response. In adrenalectomized cats, complete unloading of the baroreceptors evoked both hyperglucagonemia and hypoinsulinemia although the magnitude of the hormonal responses was diminished. In animals where the pancreas and liver were sympathectomized but the adrenal glands left intact, cutting the sinus nerves evoked a doubling of the IRG level and a slight increase in plasma glucose, but no significant change of the IRI level. I.v. infusion of adrenaline (1 γg/kg × min) or noradrenaline (5 γg/kg × min) caused pronounced increases in IRG and plasma glucose and a clear‐cut reduction of IRI. We conclude that the function of the endocrine pancreas in the cat can be influenced by variations in the blood pressure by means of a reflex control which originates from arterial baroreceptors. This reflex adjustment of the endocrine pancreas is mediated chiefly by two links of the sympatho‐adrenal system, namely by catecholamine‐release from the adrenal medulla and, more importantly. by a direct adrenergic nerve fibre influence on t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06266.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract5 types of adrenergic blocking agents with different modes of action were administered and the rate of transmitter depletion was studied in different uterine regions of guinea‐pig, and compared with that in the heart and submandibular gland by a combination of fluorescence histochemical and spectrofluorimetric methods. The tyrosine‐hydroxylase inhibitor, H 44/68, as well as reserpine and guanethidine, produced a more efficient reduction in neuronal noradrenaline in the heart and submandibular gland than in the uterus. A differential action on the sympathetic transmitter, though less clearcut, was seen with 6‐hydroxydopamine. The noradrenaline‐depleting effect of metaraminol did not distinguish between those adrenergic nerves supplying the uterus from those of the control tissues. It is suggested that the differential effects may be related to a lower activity in the uterine adrenergic nerve system, probably because this system is to a large extent composed of short adrenergic neurons, which appear to have a particularly slow transmitter t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06267.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractTissue levels of cAMP, cGMP, PGE, and PGF2βwere measured in spontaneously beating rat atria preparation at 20°C and 37°C. At 20°C the formation of cAMP increased in correlation with the markedly increased amplitude and reduced frequency. The other biochemical parameters were not significantly affected by the low temperat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06268.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY