摘要:

Experiments carried out with human foetal hypophysis or adenohypophysis cultured in combination with adrenal tissue supplied evidence that the human foetal adrenal possesses the potentiality to secrete hydrocortisone, and the human foetal hypophysis to secrete ACTH, and, further, that the hypophysis continues to produce ACTH at a low level without stimulation by the hypothalamus, at least for some time.ACTH added when hydrocortisone production had already been falling for several days invariably increased adrenocortical hormone production. Remarkably, this production reached its peak not on the day of addition, but 2 to 4 days later, although the cultures had been washed daily and no fresh ACTH had been introduced.

ISSN:0008-4212    

DOI:10.1139/y65-001

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Changes in left circumflex coronary flow, femoral blood pressure, and heart rate (ECG-Lead II) were recorded simultaneously in pentobarbitalized artificially respired open-chest dogs. A gated sine wave electromagnetic flowmeter was used for coronary flow measurements. After intravenous nitroglycerin (glyceryl trinitrate) administration in six satisfactory experiments, changes in dose–response patterns were studied. (1) Doses of 0.1 μg/kg were ineffective; doses of 1.0, 10, and 100 μg/kg induced in 10 to 15 seconds maximal increases in mean coronary flow averaging 22, 65, and 100%, respectively; blood pressure concurrently decreased showing a maximum fall (in 20 to 25 seconds) associated with reflex tachycardia; a transient initial increase in pulse pressure also occurred. (2) Coronary flow subsequently decreased, reaching below-control values; the magnitude of this decrease appeared to be related to the degree of fall in blood pressure and to the reflex tachycardia; and pulse pressure markedly decreased below the control values. (3) After intravenous injections of pentobarbitone sodium (1 and 10 mg/kg) brief initial (within 10 seconds) dose-related increases in coronary flow were also observed but associated with less-marked blood pressure decreases and no significant changes in either heart rate or pulse pressure.

ISSN:0008-4212    

DOI:10.1139/y65-002

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The uptake of Cr51chromate by thymocytes in vitro after whole body X-irradiation can be used as a sensitive quantitative criterion not only for the evaluation of early radiation damage to these cells but also as a measure of later regeneration. The development of the radiation lesion is characterized by a reduction in the in vitro uptake of Cr51and the later regeneration of new cells by an increase in Cr51uptake which is probably due to increased uptake of Cr51by the young newly formed cells in the damaged tissue which is proliferating in an attempt to repair the damage. The return of the Cr51uptake to normal is an indication of the time required for the cell population (ratio of young to older cells) to return to normal. By this technique the effect of different doses of X-irradiation on the regeneration of thymocytes has been demonstrated. Treatment with AET before whole body X-irradiation (400 r) indicated that less regeneration was necessary but the recovery time remained unchanged. Age differences produced a change in the extent of repair or regeneration but no change in recovery time.Spermatozoa showed evidence of early damage after whole body X-irradiation. This damage increased with time with no evidence of increased regeneration or repair.

ISSN:0008-4212    

DOI:10.1139/y65-003

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The effects of the antiarrhythmia agents amodiaquin and quinidine on conduction times through the atrium and the specialized conducting tissue to the ventricular myocardium have been determined from records obtained with needle electrodes suitably placed in isolated blood perfused dog hearts. Quinidine slowed conduction through each portion of the total pathway when very low concentrations were infused but had a preferential depressant effect on atrial conduction at slightly higher concentrations. Amodiaquin slowed conduction in the atrioventricular node to a greater extent than in the other parts of the common pathway at all concentrations tested. The major effect of each drug on extra-atrial conduction occurred at the atrioventricular node and at the Purkinje–myocardial junction. Amodiaquin did not induce bigeminal rhythm in the isolated heart.

ISSN:0008-4212    

DOI:10.1139/y65-004

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Procaine hydrochloride (15 mg/kg) administered intravenously raises the systemic arterial pressure in spinal cats but lowers it in cats anaesthetized with pentobarbital. The rise in blood pressure is not due to release of adrenaline or noradrenaline since a pressor response to procaine still occurs after phenoxybenzamine. Procaine also increases the blood pressure in pentobarbital-anaesthetized cats after the administration of phenoxybenzamine or reserpine. The perfusion pressure in the isolated hind limb perfused at a constant flow was increased by procaine given intra-arterially in spinal cats. In contrast, procaine lowered the perfusion pressure in the hind limb of pentobarbital-anaesthetized cats. The results are consistent with a direct vasoconstrictor effect of procaine on peripheral vessels which is masked when sympathetic vasomotor tone is high. The fall in blood pressure after procaine in pentobarbital-anaesthetized cats may be due to an effect of the drug on terminal nerve endings.

ISSN:0008-4212    

DOI:10.1139/y65-005

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Mice became more susceptible to the lethal effects of a single dose of benzyl-penicillin (penicillin G) given orally or subcutaneously after they had been fed a synthetic diet deficient in pantothenic acid for 2 weeks. Rats developed a fulminating reaction with 50% deaths within 1 week when placed upon the same diet and given a daily dose of benzylpenicillin which, over 100 days, killed 50% of controls on fox chow. The syndrome was not due to absence of pantothenic acid, since it was not altered in mice or rats by supplementation with pantothenate, nor to absence of cellulose, nor to formation on standing of toxic products in the synthetic diet. The diet contained 64% sucrose, an amount equivalent to 40 g of sucrose eaten by a rat per kg body weight per day. When this dose of sucrose was given orally at one administration, it killed over 50% of the rats. Feeding the high sucrose synthetic diet to rats for 1 month increased the reaction to subsequent daily benzylpenicillin administration. Daily administration of benzylpenicillin for 1 month to rats on fox chow, however, reduced their susceptibility when they were transferred to the synthetic diet. The results were interpreted as indicating that the reaction was due mainly to the large amount of sucrose in the synthetic diet. Change in the intestinal flora, induced by administration of benzylpenicillin, appeared to be a secondary factor.

ISSN:0008-4212    

DOI:10.1139/y65-006

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The hemodynamic effects of noradrenaline infusion (1 μg/kg min) were studied in five normal dogs and in five dogs in whom cardiogenic shock had been produced by closed-chest coronary embolization.Noradrenaline infusion caused a significant increase in arterial blood pressure, cardiac output, and mean left-atrial pressure in all animals. In the shocked group, the observed increase in cardiac output was significantly less than in the control group.The inotropic effect of infused noradrenaline was quantitated in each animal by comparing the increase in left-ventricular stroke work evoked by noradrenaline with the increase in stroke work which occurred when the mean left-atrial pressure was elevated by autologous transfusion to the level previously attained during noradrenaline infusion. In the control animals, noradrenaline increased left-ventricular stroke work an average of 91% for an average increase in mean left-atrial pressure of 5.6 mm Hg while transfusion increased left-ventricular stroke work 72% for a similar rise in left-atrial pressure. In the shocked animals, noradrenaline increased left-ventricular stroke work 120% but transfusion increased it only 35% for a similar increase in mean left-atrial pressure.It is concluded that the inotropic effect of noradrenaline is enhanced in experimental cardiogenic shock.

ISSN:0008-4212    

DOI:10.1139/y65-007

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Skeletal, cardiovascular, and urethral defects were observed in the 21-day-old offspring of Sprague–Dawley rats following administration of thalidomide (2% of diet) during the entire gestation period. The fetuses of animals which received eitherl-glutamic acid orl-glutamine (2% of diet each), in addition to thalidomide, showed essentially the same incidence and type of gross defects as those from the thalidomide-treated mothers.The ineffectiveness of these essential growth factors to reduce the embryopathy significantly is interpreted to indicate that they are not predominately involved in the teratogenic action of thalidomide in the rat.

ISSN:0008-4212    

DOI:10.1139/y65-008

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Physiological concentrations of calcium were measured in the lumen of the intestine of dogs which had been fed low, normal, or high levels of calcium. The rates of Ca absorption from duodenal, jejunal, or ileal Thiry-Vella fistulae were also determined. These data demonstrate that high Ca concentrations usually exist in the intestinal tract, and that the concentration in the lumen is directly affected by dietary level of Ca. The rate of calcium absorption per cm length of duodenum was almost double that in the jejunum or ileum, but the estimated effective Ca absorption in the whole ileum (744 mg/6 hours) exceeded that in the jejunum (144 mg/6 hours) and that in the duodenum (36 mg/6 hours).

ISSN:0008-4212    

DOI:10.1139/y65-009

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The effects of phlorizin and phloretin on amino acid reabsorption were studied using clearance techniques in dogs. At endogenous plasma amino acid concentrations no effects were demonstrable. At elevated amino acid levels phlorizin depressed the reabsorption ofL-aspartic acid andL-lysine. Phloretin depressed the reabsorption ofL-aspartic acid but had a slight enhancing effect on that ofL-lysine. No definite effects were observed onL-alanine or glycine reabsorption. These results are not predictable from the observations of other workers that in the in vitro rat kidney cortex phlorizin increases amino acid concentrating ability while phloretin depresses it. Our results are not, however, incompatible with the in vitro observations since it is theoretically possible for an agent to enhance the concentrating ability of kidney cortex, and either depress or increase tubular reabsorption, depending on whether the predominant site of action is on the luminal or basal side of the proximal tubular cells.

ISSN:0008-4212    

DOI:10.1139/y65-010

出版商:NRC Research Press    

年代:1965

数据来源: NRC