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Biomedical subjects

S Omote

Publications and source records attributed to S Omote.

At least 19 recordsLinked to original sources
PubMed1989

Selective inhibition by nifedipine of the purinergic component of neurogenic vasoconstriction in the dog mesenteric artery.

The neurogenic contractions evoked by perivascular sympathetic nerve stimulation of dog mesenteric artery consist of purinergic and adrenergic components, and these components were selectively inhibited by alpha, beta-methylene ATP and prazosin, respectively. We examined the effects of Ca antagonists on both these components in dog mesenteric arteries. Nifedipine (10(-8)-10(-6) M) inhibited the purinergic and adrenergic contractions evoked by transmural electrical stimulation, and this inhibition was more evident for the purinergic component of the response. Nifedipine was also more potent to inhibit the contractile response to alpha, beta-methylene ATP than it was to inhibit the responses to noradrenaline. Verapamil and diltiazem also inhibited the purinergic and adrenergic responses induced by transmural electrical stimulation, alpha, beta-methylene ATP or noradrenaline, but the extend of the inhibition was less than that seen with nifedipine. These three Ca antagonists had little effect on the 3H efflux evoked by electrical transmural stimulation of arteries that had been preincubated with [3H]noradrenaline. These results show that nifedipine is a selective inhibitor of the purinergic component of contractions evoked by sympathetic nerve stimulation of blood vessels.

Adenosine Triphosphate↗
PubMed1988

Long-term prognosis for patients with variant angina and influential factors.

Two hundred forty-five patients with variant angina were followed for an average of 80.5 months (range, 36-184 months). Survival rate at 1, 3, 5, and 10 years was 98%, 97%, 97%, and 93%, respectively. Survival rate without myocardial infarction at 1, 3, 5, and 10 years was 86%, 85%, 83%, and 81%, respectively. By univarite analysis, ST segment elevation in both the anterior and inferior electrocardiographic leads was the most important factor influencing survival, followed by use of calcium antagonists, left ventricular function, smoking, and alcohol intake. The variables that significantly correlated with survival without myocardial infarction were use of calcium antagonists, left ventricular function, extent and severity of coronary artery disease, coronary artery bypass surgery, and disease activity. Multivariate analysis using the Cox proportional hazards model showed that intake of calcium antagonists, extent and severity of coronary artery disease, and ST segment elevation in both the anterior and inferior leads were significant independent predictors of survival without myocardial infarction. We conclude that long-term prognosis for patients with variant angina is relatively good and that use of calcium antagonists improves it.

Adult↗
PubMed1986

A new approach for the enzymatic estimation of infarct size: serum peak creatine kinase and time to peak creatine kinase activity.

The relations of several creatine kinase (CK) variables to angiographic left ventricular ejection fraction and abnormally contracting segments in the chronic phase were examined in 2 groups of patients with a first anterior acute myocardial infarction. In group A (n = 22), emergency coronary angiography was performed and nonsurgical early reperfusion was attempted. Such an early revascularization, which was considered partially present in group B (n = 16), which received conventional therapy, shifted the CK time-activity curve to the left and altered its relation to angiographic cardiac function. At similar levels of peak CK, myocardial damage was significantly smaller in patients with successful thrombolysis than in those with unsuccessful reperfusion and conventional therapy (p less than 0.01). In patients whose infarct was considered to be moderate according to peak CK (1,000 to 3,000 U/liter), there was significant correlation between time to peak CK and left ventricular ejection fraction or percent abnormally contracting segments irrespective of their group. The results suggest that one should take into account rapid washout and shorter time to peak CK when estimating enzymatic infarct size in humans. The multivariate analysis of cardiac function with peak CK and time to peak CK resulted in a closer correlation in all patients. Such a correction in the time to peak CK may be a clinically useful approach for better interpretation of infarct size.

Aged↗
PubMed1984

Variant angina induced by alcohol ingestion.

We gave alcohol to 15 patients with variant angina to induce the attacks at the hospital. Anginal attacks were repeatedly induced in seven of them. Although the time lag between alcohol ingestion and the attacks varied widely among patients, from 1.5 to 12 hours, it was fairly constant in each patient. We carefully examined the histories of 101 patients with variant angina to become familiar with the relationship between alcohol ingestion and the attacks of angina. Seventy-one patients took alcohol in their daily lives. Nineteen of the 71 patients (26.8%) who took alcohol had a definite relationship between alcohol ingestion and the attacks. We conclude that alcohol induces anginal attacks or coronary artery spasm in not a small number of patients with variant angina.

Aged↗
PubMed1984

The effects of reperfusion of infarct-related coronary artery on serum creatine phosphokinase and left ventricular function.

In 31 patients with transmural myocardial infarction in whom coronary arteriography was performed within 8 hours after the onset of symptoms, we examined (1) the effect of restoration of coronary blood flow on serum CPK time-activity curve and (2) the relationship between cumulative CPKr and the left ventricular function in the chronic phase. We divided 31 patients into 2 groups: Group A consists of 19 patients in whom coronary reperfusion was established. Group B consists of 12 patients whose coronary artery remained occluded. In group A, the time required to reach peak serum CPK activity was significantly shorter than in group B. When comparing CPKr with percent abnormally contracting segment (%ACS) in 2 groups, correlation between CPKr and %ACS was not good, but it revealed linear relation in both group A and B. CPKr divided by %ACS (CPKr/%ACS) was significantly higher in group A than in group B. We conclude that reperfusion of infarct-related coronary artery changes serum CPK time-activity curve resulting in earlier appearance of peak serum CPK and that infarct size cannot be estimated by serum CPK level alone.

Adult↗
PubMed1983

Coronary arteriographic findings during early hours of acute myocardial infarction: response to intracoronary injection of nitrates.

We performed coronary arteriography and gave intracoronary injection of nitrates within 8 hours after the onset of symptoms of acute myocardial infarction in eighteen patients. Improved distal filling or patency of the total occluded coronary artery after intracoronary injection of nitrates occurred in 4 of 18 patients. In one of four patients the first intracoronary nitrates injection failed to release the initial total occlusion, but after intracoronary Urokinase administration, the second nitrates injection succeeded to dilate the completely occluded coronary artery. Coronary arteriography was again performed in sixteen patients in the chronic stage (4-15 weeks after the onset of acute myocardial infarction) and ergonovine maleate was injected intravenously in seven patients. Focal spasm was induced by ergonovine injection in three patients in one of whom intracoronary nitrates failed to release the complete obstruction in the acute stage. We conclude that coronary spasm as well as intracoronary thrombosis plays an important role in the production of acute myocardial infarction.

Adult↗
PubMed1983

Effect of diltiazem on left ventricular isovolumic relaxation time in patients with hypertrophic cardiomyopathy.

The effect of diltiazem on left ventricular isovolumic relaxation time was examined in 11 patients with hypertrophic obstructive and non-obstructive cardiomyopathy in a combined study using phonocardiograms and echocardiograms. Five to 10 min after intravenous injection of diltiazem (0.2 mg/kg, body weight), a prolonged isovolumic left ventricular relaxation time, which was measured from aortic component of the second heart sound to the mitral opening on the echocardiogram, decreased from 63.1 +/- 26.0 to 46.9 +/- 28.0 msec (p less than 0.01). This study suggests that diltiazem, one of the calcium blocking agents, may ameliorate the impaired left ventricular diastolic function in patients with hypertrophic cardiomyopathy.

Adolescent↗
PubMed1983

Coronary arterial spasm in ischemic heart disease and its pathogenesis. A review.

Coronary arterial spasm plays an important role iun the production not only of variant angina but, also, of resting angina other than variant angina, of some exertional angina, and of some acute myocardial infarction. Coronary arterial spasm is most likely to occur at rest, particularly from midnight to early morning, and is usually not provoked by exercise in the daytime. This is related to the fact that the tone of coronary artery is increased from midnight to early morning, whereas it is decreased in the daytime after physical activities. Coronary arterial spasm can be induced by exercise, cold pressor test, hyperventilation, Valsalva maneuver, and the administration of pharmacological agents such as sympathomimetic agents (epinephrine, norepinephrine, etc.), beta-blocking agents (propranolol, etc.), parasympathomimetic agents (methacholine, pilocarpine, etc.), ergot alkaloids (ergonovine, ergotamine, etc.), alcohol, and others, particularly in the morning when spontaneous coronary arterial spasm is most likely to occur. Diltiazem and nifedipine, calcium-blocking agents, prevent coronary arterial spasm induced by these procedures in almost all patients. Phentolamine, an alpha-blocking agent, also suppresses coronary arterial spasm induced by these procedures in 81% of the patients. On the other hand, propranolol, a beta-blocking agent, is not only ineffective in suppressing coronary arterial spasm in 82% of the patients, but aggravates coronary arterial spasm in 41% of the patients. The acute attack of coronary arterial spasm can be promptly relieved by the administration of nitroglycerin.

Angina Pectoris, Variant↗
PubMed1981

Comparison of coronary arteriographic findings during angina pectoris associated with S-T elevation or depression.

Coronary arteriographic findings during an attack of angina pectoris associated with S-T segment elevation and angina associated with S-T depression were compared in 54 patients. Thirty-eight attacks with S-T segment elevation included 2 that were spontaneous, 6 induced by methacholine, 4 by epinephrine with or without propranolol, 9 by arm exercise, 5 by hyperventilation with or without Tris-buffer infusion and 12 by ergonovine maleate. Twenty-nine of the 38 attacks were associated with total occlusion, 8 with subtotal occlusion and 1 with diffuse narrowing of a major coronary artery caused by spasm. Twenty-six attacks with S-T segment depression included 3 induced by methacholine, 13 by arm exercise, 3 by hyperventilation with or without Tris-buffer infusion and 7 by ergonovine maleate. Eight of the 26 attacks were associated with subtotal occlusion and 9 with diffuse narrowing of a major coronary artery caused by spasm; 3 attacks were associated with total occlusion of a major coronary artery well supplied with collateral vessels and 2 with total occlusion of a small coronary branch caused by spasm. Four attacks were associated not with spasm but with fixed subtotal occlusion of a major coronary artery (3 attacks) or total occlusion of a major coronary artery receiving collateral vessels (1 attack). Only 2 of the 31 patients with S-T segment elevation had collateral vessels compared with 8 of the 16 patients with S-T segment depression (p less than 0.001). It is concluded that angina pectoris associated with S-T segment elevation usually indicates more severe myocardial ischemia than angina associated with S-T segment depression.

Adult↗
PubMed1981

Alkalosis-induced coronary vasoconstriction: effects of calcium, diltiazem, nitroglycerin, and propranolol.

We examined the effects of changes in pH, Ca2+ concentration, diltiazem, nitroglycerin, and propranolol on the vascular tone of the isolated rabbit coronary artery. Stepwise increase in pH of the bath fluid caused pH-dependent increased vascular tone. Increase in Ca2+ concentration of the bath fluid also resulted in increased vascular tone, while removal of Ca2+ abolished the high pH-induced elevated vascular tone. Diltiazem and nitroglycerin suppressed the high pH-induced increased vascular tone. Propranolol in high concentrations exhibited a direct inhibitory effect on the high pH-induced increased vascular tone. We conclude that high pH induces coronary vasoconstriction principally by increasing transmembrane influx of Ca2+ and that diltiazem and nitroglycerin suppress this action.

Alkalosis↗
PubMed1981

Acute myocardial infarction induced by ergotamine tartrate: possible role of coronary arterial spasm.

A 45-year-old woman with almost normal coronary arteries suffered from acute inferior myocardial infarction after taking 2 tablets (2.0 mg) of ergotamine tartrate for headache. She had had attacks of variant angina and spasm of the right coronary artery had been demonstrated during the attack. After the recovery from myocardial infarction the intravenous injection of ergonovine maleate 0.05 mg induced spasm of the right coronary artery again. We conclude that acute myocardial infarction in this patient was probably caused by coronary arterial spasm induced by ergotamine tartrate.

Angina Pectoris↗