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Biomedical subjects

I Horikoshi

Publications and source records attributed to I Horikoshi.

At least 91 records · Page 5Linked to original sources
PubMed1983

Possible antidotes in severe intoxication with fenitrothion in rats.

We investigated antidotal effects of nine drugs against acute fenitrothion poisoning in rats. The antidotal effects were evaluated by a relief from toxic signs, an increased survival ratio and a prolonged surviving time. In the poisoning with approximate LD50 fenitrothion (500 mg/kg), oximes such as 2-PAM (2-pyridine aldoxime methiodide) and TPMM (1-(methyl morphorinium)-3-(4-hydroxyiminomethylpyridinium) propane dibromide), diphenhydramine and parasympatholytics such as atropine, scopolamine and biperiden significantly increased survival ratio and/or prolonged surviving time. These effective drugs did not sufficiently depress the toxic signs, except that the parasympatholytics markedly blocked salivation, miosis and motor ataxia. In contrast, reduced glutathione and central depressants such as diazepam and phenobarbital made the poisoning serious. In the poisoning with 100% lethal dose of fenitrothion (800 mg/kg), the parasympatholytics were more effective than 2-PAM and diphenhydramine, and they elevated the survival ratio up to 20-40%. The best therapy against the severe poisoning with 100% lethal dose of fenitrothion was confirmed to be the repeated and combined treatment with atropine and 2-PAM as established in parathion poisoning, resulting in 90% survival ratio and considerable alleviation from the toxic signs.

Animals↗
PubMed1982

Spontaneous reactivation of fenitro-oxon-inhibited plasma cholinesterase in various mammals.

It was investigated as to whether a spontaneous reactivation was also observed in fenitro-oxon-inhibited plasma cholinesterase (ChE) of human and several animals, such as mice, guinea pigs and rabbits, as previously reported in rat plasma ChE. It was found from the results that a marked spontaneous reactivation took place during storage at 37 degrees C or 24 degrees C in all of human and the animals, while these reactivations of animals were to some extent slower and slighter than that of rat. Moreover, there was little significant difference between the spontaneous reactivations observed in using acetylthiocholine and butyrylthiocholine as a substrate, although the use of the latter substrate resulted in somewhat faster and greater spontaneous reactivation only in rat. These results suggest that the spontaneous reactivation takes place in plasma pseudo ChE of various animals after inhibition with fenitro-oxon.

Acetylthiocholine↗
PubMed1981

K+ selectivity and HCl secretion in Xenopus and their relation to cAMP and Ba2+.

Doses of 1, 5, and 10 mM adenosine 3',5'-cyclic monophosphate (cAMP) applied to previously resting Xenopus gastric mucosae initiated a dose-dependent acid secretory response. Increases in the K+ concentration of the submucosal solution. [K+sm], resulted in higher acid secretory rates and concomitant lower transmucosal resistances at the indicated cAMP concentration. The transmucosal potential difference, PD, had a liner slope against log [K+sm] over the range of 20-80 mM K+sm. Values of the slope (K+ selectivity, -PD/log[K+sm]) were less than 26 mV/log for resting mucosae, and in the range of 29-58 mV/log for both spontaneously secreting and cAMP-stimulated mucosae. These values were dose dependent on the cAmP concentration. In the presence of 10 mM Ba2+ together with cAMP, the K+ selectivity and the H+ secretory rate decreased compared with the case of cAMP only.

Animals↗
PubMed1981

Difference in fenitrothion-inhibited rat plasma cholinesterase activities determined by delta pH-method and DTNB-method, due to spontaneous reactivation.

Rat cholinesterase (ChE) activities were measured by DTNB-method after an oral administration of fenitrothion, and the following facts were observed. The inhibited plasma ChE (pseudo ChE) obtained within several hours after the administration was spontaneously reactivated at 10 degrees C or over, whereas no reactivation was observed at 1 degree C. Neither red blood cell nor brain ChE (true ChE) was spontaneously reactivated. In vitro, the spontaneous reactivation was also observed in rat plasma ChE inhibited by oxon-type of fenitrothion. In case the activity of plasma ChE obtained 30 min after administration was determined by delta pH-method, the activity was higher than the actual value, because of the spontaneous reactivation taking place during an incubation for 1 h at 37 degrees C. It is suggested from these results that an utilization of delta pH-method is unsuitable for the measurement of the activity of inhibited ChE which is spontaneously reactivated.

Animals↗
PubMed1980

Ca2+ removal effects on bullfrog gastric mucosa in the presence of drugs.

Bullfrog gastric mucosa can secrete acid in vitro for more than 24 hr. In Ca2+-deficient media, the acid secretion measured by pH stat method gradually decreased to cease about 200 min after the start of immersion in the media. When A23187 or quinidine, which are known to mobilize Ca2+ from the intracellular pools, was present on the submucosal side, a prolongation of the duration of acid secretion in the absence of Ca2+ was found. Dibutyl c-AMP also induced a similar prolongation. Histamine or theophylline not only prolonged the duration of acid secretion but also transiently increased the acid secretory rate over the control level. Based upon the known fact that there are different intracellular Ca2+ compartments, i.e, one related to the process of acid secretion and the other to the maintenance of junctional complexes, the present results of drug effects were discussed especially in regard to their Ca2+ mobilizing effects. Cessation of acid secretion in a K+- and Ca2+-deficient solution occurred much more quickly than that in a Ca2+-deficient or a K+-deficient medium.

Animals↗
PubMed1977

Uptake of K+ by frog gastric mucosa from submucosal side and acid secretory rate.

The K+ content in frog gastric mucosa (K+) was measured as a function of the submucosal K+ concentration ([K+sm]) in the absence of K+ on the mucosal side. The (K+) in HCO3- buffer with 95% O2-5% CO2 gas showed that the removal of external K+ induced a 27% K+ loss from the control value of 5 mM K+sm, that there was no linear relation between (K+) and [K+sm, and that the change in the (K+) versus the [K+sm] was hyperbolic, indicating that there are two different types of K+ in the mucosa: bound and free K+.

Animals↗