摘要:

Compounds related to carnitine have been applied iontophoretically from five-barrelled micropipettes to neurons of the cerebral cortex of anesthetized cats. Both optically active and racemic mixtures of carnitine, acetyl carnitine, carnitine nitrile, and acetylcarnitylcholine had an excitatory action on cells excited by acetylcholine. The levorotatory forms were generally, but not invariably, stronger excitants than their enantiomers. Atropine administered intravenously blocked the action of all carnitines and acetylcholine. These derivatives (like ACh itself) had a depressant effect on some cells which were not excited by ACh.

ISSN:0008-4212    

DOI:10.1139/y71-001

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The effects of isoproterenol on brown and white fat were studied by analyzing the total percentage lipid of the tissue and by the fluorescent histochemical method for catecholamines in sympathetic fibers. At dosages which were well below the LD50, isoproterenol selectively emptied brown fat without affecting the white fat at all. It was suggested that the rise in free fatty acids in the blood seen afer injection of isoproterenol is partly due to an emptying of brown fat.

ISSN:0008-4212    

DOI:10.1139/y71-002

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The absorption of five14C-labeled pesticidal carbamate chemicals was studied using everted sacs of rat small intestine after verification that the technique of preparation and incubation of the sacs allowed consistent active transport of14C-glucose. All five carbamates (4-chloro-2-butynylN-(3-chlorophenyl)carbamate,1; isopropoxyphenylN-methylcarbamate,2; 4-benzo-thienylN-methylcarbamate,3; 1-naphthylN-methylcarbamate,4; and 4-dimethylamino-3,5-xylylN-methylcarbamate,5) underwent some autodegradation during incubation in Krebs–Ringer bicarbonate medium. Carbamates3and5were the most unstable. When each of the14C-carbamates was placed only in the mucosal fluid, a mixture of radiolabeled carbamate and degradation products was recovered from the serosal fluid. When the initial carbamate concentration (10−5 M) in the mucosal and serosal fluids was the same, there was a net increase in the total14C concentration (14C-carbamate plus14C-products) of the serosal fluids for carbamates2and3(and possibly1) as follows: A net mucosal to serosal transport occurred in sacs derived from the caudal intestine for carbamates1and3, and in sacs from the middle intestine for2. Substantial tissue uptake of14C occurred, particularly by those sacs which accomplished a net mucosal to serosal transport.

ISSN:0008-4212    

DOI:10.1139/y71-003

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

When plasma calcium concentrations in the rat were elevated by injection of either calcium chloride or parathyroid hormone, there was an increase in mitotic activity in the bone marrow which led to an increase in reticulocyte production and radioactive iron incorporation in the peripheral blood. Thyroparathyroidectomy produced parallel decreases in plasma calcium, bone marrow mitosis, and erythropoiesis, a situation which could be reversed by the administration of parathyroid hormone or by calcium chloride injections. Since the calcium- or parathyroid hormone-induced stimulation of bone marrow mitosis also occurred in both nephrectomized and polycythemic rats, this mitogenic action was not due to a secondary release of renal erythropoietic factor or an activation of circulating plasma erythropoietin. In contrast to calcium and parathyroid hormone, (ovine) erythropoietin did not stimulate cell division in the bone marrow within 6 h of injection.

ISSN:0008-4212    

DOI:10.1139/y71-004

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Presynaptic supersensitivity was demonstrated in isolated rat atria and perfused hearts 2 h after an intravenous injection of 6-hydroxydopamine (6-OH-DA), 100 mg/kg. This coincided with a maximum depletion of cardiac endogenous noradrenaline, a disappearance of the fluorescence of terminal adrenergic nerve fibers in the atrial myocardium, and an abolished chronotropic response to tyramine. The chronotropic response to dopamine was also significantly diminished. Maximal supersensitivity to the chronotropic effect of noradrenaline was observed 72 h after the injection of 6-OH-DA. Two weeks after the administration of 6-OH-DA, supersensitivity to noradrenaline was less marked, and the response to tyramine was restored. These changes corresponded to an increasing noradrenaline content in the heart and to the reappearance of histofluorescent fibers in the atria.

ISSN:0008-4212    

DOI:10.1139/y71-005

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Emulsified DDT was administered as a single intravenous dose to nonpregnant female rabbits at concentrations of 150, 100, 50, 25, and 12.5 mg/kg. Tremors and convulsions were observed in all animals receiving more than 12.5 mg/kg. Since DDT at 150 mg/kg proved lethal at an average time of 95.8 min, the animals receiving lower doses were sacrificed at 96 min. The results demonstrated that the distribution of an acute dose of a lipophilic insecticide to various tissues depended largely upon (1) hemodynamic factors such as the blood flow in the tissue, (2) the capillary density, and (3) the distribution of blood to various tissues from the site of injection. A positive correlation was observed between plasma levels of DDT and those found in the brain. The severity of the clinical signs of DDT poisoning coincided with the levels detected in the brain. In addition to whole brain assays, the DDT content of various regions of gray and white matter was determined in rabbits treated with 50 mg DDT/kg. The incidence of tremor coincided closely with the high levels detected in gray matter (cerebellum and neocortex). Predominantly white matter (brainstem and spinal cord) had significantly lower concentrations.

ISSN:0008-4212    

DOI:10.1139/y71-006

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Harbor seals maintained in sea water were either starved or fed graded amounts of herring of known water and total chloride contents. Total body water and exchangeable chloride in the seals were measured by initial dilution of injected tritiated water and Na36Cl. The decline in specific activities of plasma water and chloride was then followed for 12 to 14 days. Average daily fluxes of water and Cl−were calculated. Sea water ingestion was calculated from the daily chloride flux and the chloride contents of the food and sea water. In five animals fed from 0 to 1500 g herring/day, total water flux was linearly related to food intake and ranged from 500 to 1590 ml water per day. In the same animals ingested sea water and metabolic plus inspired water were also linearly related to food intake, and ranged respectively from 35 to 140 ml and 470 to 625 ml water per day. The data provide definitive evidence that starving Harbor seals derive sufficient oxidative water to satisfy the major part of their needs and that they drink very little sea water. In feeding seals the sum of preformed water and metabolic plus inspired water accounts for about 90% of the total water flux, which is comparable in magnitude to that of most terrestrial mammals. The small volume of sea water ingested by Harbor seals, and its linear relationship to food intake, show compellingly that sea water ingestion is coincident to swallowing food under water rather than due to deliberate drinking.

ISSN:0008-4212    

DOI:10.1139/y71-007

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

In vitroNa activation of the ATP hydrolyzing enzyme system in human red cell membranes and in microsomes prepared from various sites in the dog kidney was studied. Marked differences between red cell and renal ATPase were noted. Red cell ouabain-sensitive ATPase, which required 4.2 mMof Na+for half maximal activation, was markedly inhibited by concentrations of Na+of 300 mM. Medullary ouabain-sensitive ATPase required 19 mMof Na+for half maximal activation and was not significantly inhibited by 300 mMof Na+. These studies show that renal ouabain-sensitive ATPase is capable of functioning maximally in anin vitroenvironment which simulates, with respect to Na+concentration, that of the renal medullary interstitium. Thus it is not unreasonable to hypothesize that this enzyme may play a role in Na transport in the renal medulla.

ISSN:0008-4212    

DOI:10.1139/y71-008

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Small slabs of suprasylvian cortex were isolated unilaterally in six cats. After an interval of 3–4 months, single units were recorded in the slabs and in the contralateral control areas. Intravenous injections of GABA and glutamate (mostly 2–8 mmole) failed to alter the discharge of these units in any clear and predictable way that could not be ascribed to large changes in blood pressure. In this respect there was no difference between long-isolated and control neurons.14C-GABA injected i.v. did not penetrate the slabs more rapidly than the control areas. It is concluded that the convulsive tendency of long-isolated slabs cannot be ascribed to ageneralincrease in permeability of the blood–brain barrier. There was some evidence that slabs have a higher blood content than normal cortex.

ISSN:0008-4212    

DOI:10.1139/y71-009

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Changes in total brain acetylcholine (ACh) levels as related to convulsive activity were followed after the intracarotid administration of four structurally unrelated chlorinated hydrocarbon insecticides to rats. ACh levels were determined by gas chromatography. The level of ACh found in cannulated controls was 4.7 ± 0.5 (S.E.M.) μg/g fresh tissue. Lindane raised the ACh level (μg/g) to 3.5–6.7, dieldrin to 8.5–9.7, heptachlor to 6.5–10.7, and DDT to 8.8–10.9. The order of neurotoxic signs was lindane > dieldrin > heptachlor > DDT.

ISSN:0008-4212    

DOI:10.1139/y71-010

出版商:NRC Research Press    

年代:1971

数据来源: NRC