ISSN:0008-4212    

DOI:10.1139/y75-001

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Metabolic rates and rectal temperatures were continuously monitored for humans immersed in cold ocean water (4.6–18.2 °C) under simulated accident conditions. The subjects wore only light clothing and a kapok lifejacket while either holding-still or swimming. While holding-still, metabolic heat production (Hm, kcal∙min−1) was inversely related to water temperature (Tw, °C) according to the equationHm = 4.19−0.11Tw. This thermogenic response pattern is shown to be similar to that for exposure to air of the same temperature when air velocity is just over 5 m.p.h. (2.24 m/s).The thermogenic response was one-third efficient in balancing the calculated heat loss in cold water, resulting in hypothermia at a rectal temperature cooling rate (C, °C∙min−1) dependent on water temperature (Tw, °C) according to the relationC = 0.0785−0.0034Tw.Although swimming increased heat production to 2.5 times that of holding-still at 10.5 °C water temperature, cooling rate was 35% greater while swimming.A prediction equation for survival time (ts, min) of persons accidentally immersed in cold water (Tw, °C) has the formts = 15 + 7.2/(0.0785−0.0034Tw), based on the findings of this study, and it is compared to pre-existing mod

ISSN:0008-4212    

DOI:10.1139/y75-002

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The effects of stress due to brief (4–5 min) ether and pentobarbital anesthesiavs. decapitation on assays of seven enzymes in homogenates of synovium, articular and epiphyseal cartilage, and metaphyseal and cortical bone were compared. Etherization caused twofold changes in synovial and articular cartilage G-6-PDH, LDH, CPK, glutamic DH, and ICDH based on tissue dry weight and DNA content. Pentobarbital anesthesia produced only slightly lower activities, per gram DNA, of LDH, acid phosphatase, and glutamic-DH in cortical bone. Epiphyseal cartilage metabolism was unaffected by either mode of anesthesia. No differences could be detected between the levels of enzyme activities of the several tissues taken from rats that had been decapitated or anesthetized with pentobarbital. The changes in enzyme activities suggested that pentobarbital was non-stressful and appropriate to metabolic studies in the skeleton.

ISSN:0008-4212    

DOI:10.1139/y75-003

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The perfused central artery of the rabbit ear was less sensitive to extraluminal than to intraluminal noradrenaline, but the reverse was true for metaraminol, methoxamine, metanephrine, and isoproterenol. No difference was noted between the extraluminal and intraluminal potency of phenylephrine. Cocaine potentiated the effect of extraluminal and intraluminal noradrenaline, but decreased that of intraluminal phenylephrine. Irrespective of the route of administration, the constrictor potencies of other sympathomimetic amines were not affected by cocaine. Arteries of reserpine-treated rabbits were supersensitive to extraluminally and intraluminally applied noradrenaline and phenylephrine, but they were not supersensitive to metaraminol. 6-Hydroxydopamine effectively destroyed adrenergic nerve endings of the central ear artery and increased its responses to both extraluminal and intraluminal noradrenaline and phenylephrine. However, only the constrictor potencies of intraluminally applied metaraminol and methoxamine were enhanced by 6-hydroxydopamine. The apparent discrepancies between the results obtained by various procedures that eliminate or impair the nerve uptake process suggest that the difference in the constrictor potency of extraluminal and intraluminal sympathomimetic amines is probably unrelated to their uptake by nerves located in the adventitio–medial junction of the artery.

ISSN:0008-4212    

DOI:10.1139/y75-004

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Several aryl and heteroaryl hydrazides were synthesized and evaluated for their inhibitory effects on glutamic acid decarboxylase (GAD), GABA-α-oxoglutarate aminotransferase (GABA-T), and monoamine oxidase (MAO) enzyme systems in chick brain 24 h after their intramuscular administration (0.75 mmol/kg). All compounds produced a reduction in GAD, GABA-T, and MAO activity. Structure–activity relationships indicated that the ring structure had a greater influence on the degree of GAD and GABA-T inhibition than did the N′-terminal group. In contrast, structural requirements for MAO inhibition were much more restrictive. The intramuscular administration of benzoic acid hydrazide to chicks 24 h prior to their being exposed to oxygen at high pressure provided significant protection against the onset of the hyperbaric oxygen-induced seizures.

ISSN:0008-4212    

DOI:10.1139/y75-005

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Brewster angle reflections from oxidized cholesterol membranes are described in terms of uniaxial crystal model. The refractive indices perpendicular and parallel to the membrane are 1.515 and 1.555, respectively. A multilayer model was also considered; however, under the approximations used, both models are equivalent and cannot be distinguished. Egg albumin and hexadecyltrimethylammonium bromide altered the refractive indices while 2,4-dinitrophenol and valinomycin addition did not produce a detectable change.

ISSN:0008-4212    

DOI:10.1139/y75-006

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The arterio-alveolar nitrogen differencehas been assessed in 27 normal adult subjects aged 20–60 years. As it may be assumed that venous and arterialare identical, we have used a sample of venous blood. There is a significant positive correlation betweenand age. As the increase ofwith age resembles that found in the literature for, we conclude that the latter may be explained by increasinginequality within the lung.

ISSN:0008-4212    

DOI:10.1139/y75-007

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Hemorrhagic shock was produced by bleeding conscious rats to a mean arterial pressure of 40 mm Hg, which was maintained for 2 h. Basal glucose uptake by isolated soleus muscle from normal rats and rats subjected to hemorrhagic shock ('shock' muscles) increased with the increase in medium glucose concentration. Uptake values were similar in both groups of muscles. This indicates that there were no alterations in the basal glucose carrier mechanism during shock. Whereas insulin (0.1 U/ml) stimulated glucose uptake in control muscles under aerobic as well as under anaerobic conditions, it had no stimulatory effect in 'shock' muscles under either environment. Maximal stimulation of glucose uptake in 'shock' muscles was observed at an insulin concentration of 0.2 U/ml. The ability of muscle to bind insulin was not altered during shock. The present experiments indicate that insulin responsiveness to tissues is altered in shock. This could be due to alterations in the insulin sensitivity of the glucose carrier mechanism during shock.

ISSN:0008-4212    

DOI:10.1139/y75-008

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The influence of chronic hyper- and hypothyroidism on the uptake and retention of tritiated noradrenaline ([3H]NA) and on the endogenous noradrenaline (NA) content of various adrenergically innervated tissues was studied in thyroidectomized and sham-operated euthyroid rats. Half of the thyroidectomized rats were treated daily with thyroxine (25 μg/kg) for 3 or 12 weeks to simulate a condition of chronic hyperthyroidism, while the other half was left untreated to form a hypothyroid group. The body weight and the heart rate of each rat were measured at the end of each experiment, and in addition, at the end of the 3 week experiment, the oxygen consumption and the plasma thyroxine levels were measured to confirm the thyroid state of the animals. At the end of both experiments, each animal was given an intravenous injection of [3H]NA and the [3H]NA and the total endogenous NA content of the heart and various other adrenergically innervated tissues were measured on a timed schedule, to compare the initial accumulations and the rates of efflux of [3H]NA under different thyroid states. Although the hyperthyroid rats had higher heart rates and heart weights, they were not significantly different from the euthyroid controls with respect to their body weights, tissue NA content, or accumulation and efflux rates of [3H]NA. In contrast, the hypothyroid rats showed significantly lower heart rates, body weights, and heart and other tissue weights, but higher tissue concentrations of NA and rates of efflux of [3H]NA than the euthyroid group. In the hypothyroid state, the NA turnover appeared to be increased as the [3H]NA efflux rate was increased from the hearts and adrenal glands. There were no significant differences between the results of the 3 week and the 12 week experiments and no evidence that prolongation of the hyperthyroid state gave different results from those found by other workers who used much shorter treatment periods and larger doses of thyroxine to develop hyperthyroidism.

ISSN:0008-4212    

DOI:10.1139/y75-009

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Glucagon causes marked elevations of glomerular filtration rate (GFR) in dogs when administered intravenously (i.v.) in small doses. The associated natriuresis is thought to be entirely due to increments in the filtered sodium load. In this study, renal denervation, thyroparathyroidectomy, and blockade of cholinergic, α- and β-adrenergic, dopaminergic and histaminergic receptors did not prevent the usual glucagon-induced elevations of GFR or rate of sodium excretion (UNaV). This effect of glucagon was not mediated through the release of cyclic AMP, or by plasma compositional changes of Ca2+, K+, or amino acids. Pure porcine secretin, in doses of 5–10 μg/min delivered either i.v. or into the left renal artery did not alter GFR; clearance rate ofp-aminohippurate (CPAH) or UNaV in either hydropenic or saline-loaded dogs. Nor did this polypeptide, structurally very similar to glucagon, abolish the effect of glucagon on GFR. It did, however, partially inhibit the glucagon-induced natriuresis, presumably by preventing a previously undetected glucagon action on tubular reabsorption of sodium.

ISSN:0008-4212    

DOI:10.1139/y75-010

出版商:NRC Research Press    

年代:1975

数据来源: NRC