摘要:

The adaptive responses to 12 weeks of accommodated resistance training were compared in females (n= 11) and males (n= 11). They performed four to five sets of six maximum bilateral coupled concentric and eccentric quadriceps muscle actions at 1.05 rad s‐1three times per week. Uni‐ and bilateral concentric and eccentric peak torque at different angular velocities (0.52, 1.57 and 2.62 rad s‐1), three repetition maximum half‐squat and vertical jump height were measured before and after training.Both groups displayed marked increases (P<0.05) in concentric and eccentric peak torque at all angular velocities. The relative increases (P<0.05) in unilateral concentric (26vs.26%) and eccentric (28vs.36%) peak torque across speeds were similar in females and males. The corresponding increases (P<0.05) in bilateral concentric and eccentric peak torque across speeds were 20vs.28% and 24vs.39% respectively. The three repetition maximum half‐squat (20vs.25%) and vertical jump height (10vs.8%) increased (P<0.05) equally in females and males.These results suggest that the overall increases in concentric and eccentric peak torque and functional strength, in response to short‐term accommodated resistance training, occur at a rate that is independent of sex. The torque‐velocity relationship, however, appears to change in males suggesting a relatively greater enhancement of maximum voluntary force in the slow‐speed, hi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09063.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

To determine whether there may be an abnormality in sympathetic nerve activity in response to physical and psychological stressors, we microneurologically recorded muscle sympathetic nerve activity in 11 normotensive and 9 borderline hypertensive, age‐matched men. Supine blood pressure, plasma levels of epinephrine and norepinephrine and muscle sympathetic nerve activity were measured before and during a cold pressor test or a mental arithmetic test. The resting basal values of muscle sympathetic nerve activity, blood pressure and plasma epinephrine were significantly higher in the borderline hypertensives than in the normotensives (P<0.05). Plasma norepinephrine levels tended to be higher in the borderline hypertensives than in the normotensives but not to a significant extent (P<0.10). The cold pressor test produced significantly exaggerated pressor and muscle sympathetic nerve responses (P<0.05) with a trend towards an increase in plasma norepinephrine (P<0.10) in the borderline hypertensives as compared with normotensives. The mental arithmetic test produced significantly enhanced pressor and plasma epinephrine responses in the borderline hypertensives as compared with the normotensives (P<0.05). During the mental arithmetic test the muscle sympathetic nerve activity decreased significantly in the normotensivesP(<0.05) but not in the borderline hypertensives. These findings indicate that in people with borderline hypertension an abnormality exists in sympathetic nerve activity at rest and in response to stressor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09064.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The present study was performed to characterize cardiovascular responses to isoprenaline and the influence of autonomic reflexes on these reponses. Nine healthy volunteers received infusions and bolus injections of isoprenaline before and after ‘autonomic blockade’ produced by intravenous atropine 0.04 mg kg‐1and clonidine 300 μg. Heart rate, blood pressures, systolic time intervals and various echocardiographic measures of cardiac contractility were registered. No significant differences in responsiveness to isoprenaline were seen when infusions were repeated on the same day without ‘autonomic blockade’. After ‘blockade’, Δ responses at 1 nmol 1‐1isoprenaline (infusions) were increased for diastolic blood pressure and decreased for systolic blood pressure and stroke volume. Bolus injections of 2 μg isoprenaline caused enhanced Δ responses after ‘autonomic blockade’ of diastolic blood pressure, left ventricular diameter in systole, ventricular circumferential fibre shortening, mean posterior wall velocity (Vmean pw), stroke volume, systemic vascular resistance, electromechanical systole (QS2) and pre‐ejection period. Systolic blood pressure decreased, in contrast to a small increase without ‘blockade’. These findings are explained by differences in haemodynamic effects of isoprenaline and by the dependence of responses on reflexes when isoprenaline is administered in different ways. When heart rate was increased by bolus doses of atropine, in the presence of β‐blockade (propranolol), pre‐ejection period and left ventricular diameter in systole were unaffected, andVmean pwand ventricular circumferential fibre shortening showed only small increases (compared with alterations induced by isoprenaline). However, left ventricular ejection time, QS2and ejection time (by echocardiography), were markedly dependent on heart rate alterations. Thus, pre‐ejection period, left ventricular diameter in systoleVmean pwand ventricular circumferential fibre shortening are parameters which can be useful in order to evaluate cardiac β

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09065.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Six normal men performed cycle ergometer exercise from 50 W to 125 W in a room maintained at 26 d̀C. Capsaicin was introduced by iontophoresis into the forearm skin. Forearm skin blood flow (FSBF) during graded exercises before and after capsaicin treatment was measured by laser Doppler flowmetry. Forearm skin blood flow before capsaicin treatment increased depending on the intensity of exercise. However, forearm skin blood flow 24 hours after capsaicin treatment scarcely increased during graded exercise. The cause of this capsaicin effect was discussed

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09066.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Lithium (Li+) absorption across the low‐resistance epithelium of the rabbit gall‐bladder was studied in order to elucidate possible routes and mechanisms of Li+transfer. Li+at a concentration of 0.4 mM in both mucosal and serosal media did not affect isosmotic mucosa‐to‐serosa fluid absorption. At this low concentration net mucosa‐to‐serosa Li+absorption was insignificant when the ambient Na+concentration was 115 mM, although the gall‐bladder had a significant Li+permeability (2.7 times 10‐5cm‐1) and a significant mucosa‐to‐serosa Li+gradient developed as a result of fluid absorption. Net Li+absorption was induced at reduced mucosal Na+concentrations (by lowering the Na+concentration down to 50 mM with or without substitution with sucrose, or by adding sucrose to the mucosal medium). This Li+absorption occurred even in the absence of a mucosa‐to‐serosa Li+gradient. Na+and Li+absorptions occurring at 50 mM Na+were inhibited to the same degree by mucosal 1 mM amiloride. Substitution of 5–50 mM (44%) Na+by Li+in the external medium dose‐dependently depressed Na+absorption by up to 76%, while substitution by 50 mM choline had no significant effect. Li+inhibition of Na+absorption was elicited from the mucosal side and was not accounted for by compensatory Li+absorption; water and Na+absorption rates decreased nearly in parallel. The effects of 0.4 mM amiloride and of substitution with 20 mM Li+were only partly additive. It is concluded that Li+absorption in the rabbit gall‐bladder cannot be explained by passive (paracellular) transport, but must be the result of transcellular, active transport. Both at low and at high concentrations Li+may enter the cell via an Na+/H+exchanger in the apical cell membrane. At high concentrations Li+may inhibit Na+absorption by interference with the exchange mechanism and/or via effects at the cytoplasmic level. The Li+transfer mechanism across the basolatera

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09067.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A secretion of parotid saliva in the anaesthetized rat in response to stimulation of the parasympathetic nerve occurs in the presence of atropine and adrenoceptor antagonists, albeit reduced and transient in the face of continuous high‐frequency stimulation (40 Hz). In non‐atropinized rats prolonged stimulation of the parasympathetic nerve at a high frequency (40 Hz, 40 min), aiming at depletion of the neuronal stores of transmitters thought to be responsible for the non‐adrenergic, non‐cholinergic (NANC) secretion of parotid saliva, was performed. The magnitude of the secretory response to various stimulation frequencies (0.2–60 Hz) applied to the parasympathetic nerve was assessed before and after the period of high‐frequency stimulation. The second time, the frequency‐response curve was shifted to the right and, moreover, the initial maximal secretory response was not reached. Control experiments suggested that this reduction in secretory responses could be attributed neither to impaired cholinergic neurotransmission nor to decreased responsiveness of the secretory cells. The secretory responses to parasympathetic nerve stimulation after high‐frequency stimulation are thought to be evoked by acetylcholine predominantly. When these responses were compared with (1) those obtained before high‐frequency stimulation and thought to be evoked by acetylcholine and non‐adrenergic, non‐cholinergic transmitters in conjunction and (2) those depending on non‐adrenergic, non‐cholinergic transmitters only it appears that the non‐adrenergic, non‐cholinergic transmission contributes to the parasympathetic secretory response at a frequency (0.2 Hz) far below threshold frequency (5 Hz) for the non adrenergic, non‐cholinergic evoked secretory response. At frequencies below 20 Hz it appears that acetylcholine and non‐adrenergic, non‐cholinergic transmitters interact positively thereb

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09068.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Controversy exists regarding the validity of various techniques for estimating rates of protein synthesisin viva.In the present report, we have compared estimates of hepatic protein synthesis in normal mice with a pulse labelling of [1‐14C]leucine and calculated hepatic protein synthetic rates in a conventional two‐pool model and in a five‐pool compartment analysis. Results obtained with pulse labelling were also compared to those obtained in animals receiving a flooding dose of 1.5 μmol L‐phenylalanine and 0.4 μCi [U‐14C]phenylalanine per gram of body weight or 1.0 μmol L‐leucine and 0.4, μCi [I‐14C]leucine per gram of body weight. Estimates of protein synthesis were calculated with plasma free amino acid, liver acid‐soluble fraction and acylated tRNA specific radioactivities as being representative of the precursor pool for protein synthesis.Rates of hepatic protein synthesis obtained with pulse labelling and either leu‐tRNA or acid‐soluble fractions of liver leucine as the precursor for protein synthesis gave similar results (37 pL 5 vs 42 pL 5% per day) in a two‐pool model, but disagreed in a fivepool model (37 pL 5 us 6 pL 2% per day). Estimates based on plasma enrichment in leucine were only one fifth of values obtained with tRNA in labelling experiments. When the plasma pool with tracer amino acids was used to indicate the precursor labelling of protein synthesis, values obtained with the flooding dose of either phenylalanine or leucine agreed with those obtained with pulse labelling and enrichment in tRNA (30 pL 3 nmol min‐1us28 pL 4 nmol min‐1); with however no agreement when the enrichment in the liver mixed tissue pool was used (76 pL 5 nmol min‐1). Complete equilibration of the amino acid pools did not occur despite flooding.Therefore, the flooding technique may only represent an approximate method to measure protein synthesis in vivo, although it gives absolute values that agree well with results from labelling techniques based on tRNA enrichment provided the plasma pool is u

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09069.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

This study was undertaken to elucidate whether duct cells in the pancreas contain acidic cytoplasmic compartments regulated by secretion. Microdissected pancreatic ducts from pigs were examined by acridibe orange (AO) and 2′, 7′‐biscarboxyethyl‐5(6)‐carboxyfluorescein/tetraacetioxymethyl ester (BCECF/AM) epifluorescence microscopy. Estimated cytoplasmic pH using BCECF fluorescence was 7.43pL0.04 and was not changed by altering CO2tension in the incubation mdium. The epithelium of acridine orange incbated peripheral interlobular pancreatic ducts exhibited green and fluorescence was sen in resting pancreatic ducts and was greatly accentuated by raising CO2in the incubation medium with chloroqyuine or NH4Cl or the protonophores carbonyl cyanidep‐trifluoromethoxyphenylhydrazone (FCCP) or carbonyl cyanideM‐chlorophenylhydrazone (CCCP), leaving uniform gren fluoresence. These findings suggest that pancreatic duct cells contain CO2‐dependent acidic compartments which vanishduring seceatin stimulation and which may be cytoplasmic

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09070.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

After 30 minutes spent in an upright posture six healthy male subjects underwent two 130‐minute experiments in a supine posture, the first in thermoneutral conditions (TC) and the second, 15 days later, in a hot environment (HE) in order to obtain a water loss of 2.5%) body weight. In thermoneutral conditions, the supine posture induced plasma volume expansion, resulting in slightly lowered plasma vasopressin (AVP) levels and higher plasma atrial natriuretic peptide (ANP) levels, compared to the values obtained in the upright posture (P<0.05). During hot environment, the sweating‐induced dehydration led to a significant reduction of plasma volume expansion and to an increase in rectal temperature and plasma osmolality (P<0.05). Plasma vasopressin levels were higher at the end of the heat exposure (P<0.05) but natriuretic peptide levels did not change, compared to the values observed in the upright posture. These data suggest that plasma volume reduction induced by thermal dehydration may limit the natriuretic peptide release, which occurs after changing from the upright to a supine posit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09071.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The distribution of membrane‐bound carbonic anhydrase, CA IV, was studied in human kidneys by an indirect immunoperoxidase method using a rabbit polyclonal antibody directed against human kidney CA IV. Clear staining of CA IV was found in the apical cell borders of some cells in the cortical and medullary segments of the collecting ducts, presumably the A type of intercalated cells. Weak staining for CA IV was located in the interior of a number of collecting duct cells and in the basolateral regions of the proximal convoluted tubules. However, no staining was found in the brush border of the same tubules. This is a surprising finding, since evidence for carbonic anhydrase activity has been found biochemically and histochemically both in isolated brush‐border and baso‐lateral membranes. Further work is needed to clarify this matter. The endothelium of the peritubular capillaries also stained for

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09072.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY