Protoveratrin A, BおよびVeratridineの臨床的,ならびに,実験的観察,とくに,その血行力学的数値と,不正拍について
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概要
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So far as the heart of dog is concerned, there exists some significant difference in the modes of pharmacological action between veratridine and protoveratrine. The intravenous injection of veratridine causes moderately both bradycardia and arterial hypotension. By the intravenous application, the hypotension of veratridine is rather shorter in duration than that of protoveratrine at the equimiligram. The sufficient doses of each drug show a fairly transitory effect in depressing pulmonary ventilation, mainly respiratory rates. After bilateral cervical vagotomy there can be found practically no longer any bradycardia and hypotension of veratridine, therefore these actions of veatridine may appear at least largely via Bezold-Jarisch's reflex as many authors emphasize. The bradycardiac action of protoveratrine is also abolished by the bilateral vagotomy, but the hypotension still remains to a certain extent. However in the same dog the denervation of bothsided carotid sinus areas after the bilateral vagotomy almost completely surpresses the protoveratrine hypotension at the same amount. The direct administration of protoveratrine to the carotid sinus regions causes fall in blood pressure and reduces the heart rates, consequently protoveratrine is likely to be active not only on Bezold-Jarisch's receptors but also on carotid sinus baroreceptors. After the bilateral resection of carotid sinus nerves and cervical vagosympathetic trunks, the intravenous injection of further increased dose of protoveratine or veratridine enhances the secondary rise of blood pressure and the active heterotopic tachycardia, but the respiratory inhibition remains almost unchanged. Such a difference in pharmacological action between veratridine and protoveratrine may be data to go upon the availability of the combined use of two drugs. In man the therapeutic doses of protoveratine A and B cause the sinus bradycardia which can be easily inhibited by atropinization. The depressant actions of protoveratine A or B is practically independent from its bradicardiac action. After the atropinization the intravenous injection tends to elicit not seldom the slight extent of the transitory sinus tachycardia. It is very rarely observed that the depressant action can be hardly recognized despite of the bradycardia; however even in such a dissociation when the dose of protoveratrine is augmented, the blood pressure level may be usually lowered. A large amount of protoveratrine may cause besides various degree of heart block, extrasystoles and allied arrhythmias. In man such arrhythmias may begin to appear 15" after the intravenous injection and then persist for some minuetes. The patients oversensitive to digitalis is used to show also the hypersensitivity to the protoveratrine. When blood pressure is sufficiently lowered, there takes plase sometimes transitorily a high steeple T in ecg., or an increase in the positivity of T which was previously flat or negative; these facts can be, as a rule, earily found,in T of Wilson's levogram. But on the other hand, there may be observed also a minority of cases which accentuate the left ventricular strain pattern in hypertension by the use of protoveratrine. In short, the response of T to protoveratrine is fairly variable from case to case. By the administration of protoveratrine, cardiac output increases or decreases in its amount as the case may be. This change in cardiac output shows no intimate relationship to that in pulse rate. Generally the augmented left cardiac work develops a tendency to be reduced. Protoveratrine does not essentially influence upon the modes of responses of orthostatic hypotension and tachycardia. Protoveratrine does not markedly modify the result of cold pressor test, even if it were so, it inhibits merely to slight extent. There can not be seen any striking change in GFR and RBF, yet protoveratrine reduces infrequently them, to certain degree.
- 千葉大学の論文
- 1958-11-28