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Biomedical subjects

T Hobara

Publications and source records attributed to T Hobara.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of acute 1,1,1-trichloroethane inhalation on aortic nerve impulse and blood pressure.

Effects of 1,1,1-trichloroethane (1,1,1-TCE) inhalation on the afferent impulse of the aortic nerve and aortic blood pressure were investigated in anesthetized dogs. In acute inhalation experiment, the threshold concentration of 1,1,1-TCE required to produce a decrease in the aortic nerve activity was approximately 0.4% in inspired air. Moreover, this threshold level and the threshold concentration required to produce a decrease in aortic blood pressure were identical in value. The aortic nerve activity obviously decreased and at the same time was accompanied by a marked decrease in aortic blood pressure following inhalation of high 1,1,1-TCE concentration. These results suggest that the afferent pathway of aortic baroreflex may be operated at a concentration of more than 0.4% in inspired air. It is further suggested that baroreceptor reflex plays a major role in the control of arterial blood pressure following acute 1,1,1-TCE inhalation in anesthetized dogs.

Action Potentials↗
PubMed1984

Experimental study on the pulmonary absorption and excretion of toluene.

Three exposure levels of toluene were inhaled by dogs for 1 h. Toluene concentrations in expired air, arterial blood and venous blood were repeatedly measured. Absorptions of toluene within one hour of exposure were 25, 56 and 74 mg/kg at 700, 1500 and 2000 ppm respectively (absorption ratio = 27%). The cumulative excretion one hour after exposure was 63% of the absorped material at all three exposure levels. Multiple regression analyses were performed to interconnect the independent variables.

Absorption↗
PubMed1984

[An experimental examination of extra-hepatic metabolism of trichloroethylene in dogs].

To investigate the extra-hepatic organs metabolism of trichloroethylene, the extra-hepatic circulation in dogs was established by operating on the portal vein-right femoral vein bypass and other locations. These dogs were exposed for one hour to trichloroethylene at concentrations of 700 ppm. Metabolite (trichloroethanol (F-TCE), trichloroacetic acid (TCA) and total trichloroethanol (T-TCE) changes in serum and urine were measured from the beginning of exposure until one hour after termination, and compared with previous data as control. The following results were obtained. This operation method gave a very slight invasion on dogs. About two hours after the operation, no abnormal findings were observed clinically or physiologically. This method was considered to be one of the best for study of the metabolism of chemical substances in the extra-hepatic organs of dogs. The produced ratios of F-TCE, TCA and T-TCE in extrahepatic organs were about 60, 10 and 30% exposure to trichloroethylene at 700 ppm, respectively.

Animals↗
PubMed1984

[Peripheral vasodilator effect of 1,1,1-trichloroethane inhalation].

It is presumed that systemic hypotension resulting from high concentration of 1,1,1-trichloroethane (1,1,1-TCE) inhalation may be induced by functional depression of the central nervous system. However, it is still uncertain the possibilities that one of the site of action where 1,1,1-TCE acts in systemic hypotension existed in the portion without the central nervous system. The present experiment was performed to investigate the role of the peripheral vessels as a site of action in the systemic hypotension following 1,1,1-TCE inhalation. The right hindlimb of a dog anesthetized with sodium pentobarbital (25-30 mg/kg, intravenously) was amputated at the central level of the thigh bone leaving muscles and nerves. The isolated hindlimb was perfused with blood at a constant flow rate using a pump. Venous blood circulated in the isolated hindlimb was returned to the femoral vein. To measure the perfusion pressure of the isolated hindlimb, a small catheter was inserted into the artery and was connected to a pressure transducer (Nihon Kohden, MPU-0.5). In this perfusion experiment, the changes in perfusion pressure following 1,1,1-TCE inhalation are shown to be the reaction of peripheral vessels only as the site of action of 1,1,1-TCE. In other words, the effects of 1,1,1-TCE on central nervous system could be completely removed. Various concentrations of 1,1,1-TCE vapor, made by an inside circuit vaporizer, were inhaled during a period of approximately 2 min. Perfusion pressure was continuously recorded before, during and after the termination of inhalation.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗
PubMed1983

[Uptake, elimination and metabolism of tetrachloroethylene in dogs].

Fifteen dogs were made to inhale tetrachloroethylene at concentrations of 700, 1,500, 2,000 ppm for one hour, and the changes in its concentrations in the expired air, the arterial blood, the venous blood and its metabolites (trichloroacetic acid (TCA), free-trichloroethanol (F-TCE) ) in the serum and the urine were measured from the beginning of exposure until two hours after it had been terminated. The results obtained were as follows. Levels of cumulative intake of tetrachloroethylene after one hour (i.e., at the termination of the inhalation) were 47 mg/kg for 700 ppm, 79 mg/kg for 1,500 ppm and 103 mg/kg for 2,000 ppm. Mean cumulative excretion ratio against the total intake two hours after the termination of the inhalation was 69% as the average for the three exposure levels. Mean ratio of the total absorption to the total intake for one hour was 23% as the average for the three levels. Using the above results, the authors did the multiple regression analysis of cumulative absorption (Y1) as well as cumulative excretion (Y2) taking two independent variables (X) and (Insp. or Z), which are as follows. a) During the exposure period, Y1: cumulative absorption (mg/kg), X1: exposure duration (min), Insp.: levels of solvent value in the inspired air (microgram/ml), log Y1 = -2.2819 + 0.5681 log X1 + 0.8232 log Insp. b) During the post exposure period, Y2: cumulative amounts of solvent excreted (mg/kg), X2: time in minutes after exposure end (min), Z2: cumulative absorption when exposure ended (mg/kg), log Y2 = -2.016 + 0.6976 log X2 + 0.7397 log Z2.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1982

[Experimental examinations and toxicokinetic analysis of the absorption and excretion of 1,1,1-trichloroethane by the lung].

Of fifteen dogs each five of them inhaled 1,1,1-trichloroethane (1,1,1-TCE) at the levels of 700, 1500 and 2,000 ppm respectively for one hour. Changes in 1,1,1-TCE concentrations in the expired air, arterial blood and venous blood of dogs were measured from the beginning of exposure until one hour after the end of exposure. The results obtained were as follows. 1. Cumulative uptakes of 1,1,1-TCE in one hour exposure were 27.3 mg/kg at 700 ppm, 44.7 mg/kg at 1,500 ppm and 71.2 mg/kg at 2,000 ppm. 2. Excretion ratios of 1,1,1-TCE in one hour after the exposure were 66-71% at all the three levels of exposure. 3. During the exposure, highly significant negative correlation was seen between arterial/venous blood concentration ratio and expired/inspired air concentration ratio. In the post-exposure period, highly significant positive correlations were seen between expired air concentration and venous or arterial blood concentration. 4. The mean ratio of the total absorption value to the total inspired value was 14% at all the three levels of exposure. 5. From these results, the authors examined the multiple regression equations with two independent variables x and z which are shown as follows. a) During the exposure period, Y1: Cumulative absorption solvent value by the dog (mg/kg) X1: Time of exposure (min) Z1: Level of the solvent value in the ambient air (microgram/ml) log Y1 = -0.526 + 0.622 log X1 + 0.905 log Z1 b) Post exposure period, Y2: Cumulative excreted solvent value by the dog (mg/kg) X2: Time after the end of exposure (min) Z2: Cumulative absorbed solvent value by the dog at the end of exposure (mg/kg) log Y2 = -2.300 + 0.609 log X2 + 0.858 log Z2 We assumed that both equations are very fit and significant.

Animals↗