Takao Chibana

Increased QT dispersion and cardiac adrenergic dysinnervation in diabetic patients with autonomic neuropathy

Diabetic patients with autonomic neuropathy showed an increase in QTc dispersion correlated with cardiac adrenergic dysinnervation. A larger prospective study in a diabetic population is needed to assess whether QT dispersion increases the risk of arrhythmogenicity through autonomic dysfunction.

Enhanced insulin response relates to acetylcholine-induced vasoconstriction in vasospastic angina

OBJECTIVES This study investigated whether insulin response to an oral glucose load correlates to acetylcholine-induced coronary vasoconstriction in subjects with vasospastic angina. BACKGROUND It has been suggested that coronary vasospasm is caused by augmented vascular responsiveness possibly exerted by atherosclerosis. Recently, insulin resistance syndrome has been proposed as a major promotor of atherosclerotic disease, potentially enhancing vascular smooth muscular tone. METHODS Among subjects with angiographically smooth coronary arteries, we selected 14 subjects with vasospastic angina and 14 age- and gender-matched subjects with atypical chest pain. We compared coronary vasomotor response to acetylcholine infusion, glucose and insulin responses to an oral glucose load (75 g), serum lipid concentrations, obesity, heart rate, blood pressure and smoking habits in both groups. RESULTS Fasting serum insulin concentrations and insulin response were higher in subjects with vasospastic angina than in those with atypical chest pain; however, glucose tolerance, obesity, heart rate, blood pressure and smoking habits did not differ between groups. In subjects with vasospastic angina, nearly all coronary segments, except distal segments of the left circumflex coronary artery, were constricted at peak acetylcholine infusion (20 to 100 micrograms), whereas all segments were dilated in subjects with atypical chest pain. Regression analysis for both groups demonstrated a correlation between coronary vasoconstriction and fasting serum insulin concentrations (r = 0.52, p < 0.01), insulin response (r = 0.71, p < 0.001), serum triglyceride concentrations (r = 0.51, p < 0.05) and atherogenic index (r = 0.44, p < 0.05). CONCLUSIONS Results show that acetylcholine-induced coronary vasoconstriction in subjects with vasospastic angina correlates with hyperinsulinemia and enhanced insulin response, suggesting insulin resistance syndrome as a feature of vasospastic angina.

Cardiovascular Effect of a Senso (Toad Venom)-Containing Drug in Anesthetized Dogs (2): Influence of Propranolol

Effects of a Senso (toad venom)-containing drug KY on systemic hemodynamics were examined, and participation of beta-adrenoceptor in its action was evaluated by using propranolol in anesthetized dogs. KY produced a positive inotropic action, and decreased total peripheral (TPR) and coronary vascular resistances (CR), while renal vascular resistance (RR) was increased. After propranolol, KY significantly increased TPR, CR, vertebral vascular resistance and RR. KY-induced positive inotropic action was partly diminished but not abolished by beta-blockade. These results indicate that the beta-adrenergic action may be involved in the vasodilating effect of KY and partly in the positive inotropic action.