A pharmacologic activator of endothelial KCa channels improves coronary function in the hearts of type 2 diabetic rats (1078.10)

Abstract

Endothelial dysfunction is a common early pathogenic event in patients with type 2 diabetes (T2D) who exhibit cardiovascular disease. In the present study, we have examined the effect of SKA‐31, a positive modulator of endothelial Ca2+‐activated K+ (KCa) channels, on total coronary flow in isolated hearts from Goto‐Kakizaki (GK) rats, a non‐obese model of T2D and age‐matched controls. Total coronary flow and left ventricular developed pressure were monitored simultaneously in spontaneously beating, Langendorff‐perfused hearts. Acute, bolus administrations of bradykinin (BK, 1 μg) or adenosine (ADO, 10 μg) increased coronary flow, and these responses were blunted in diabetic hearts at 10‐12 and 18‐20 weeks of age. In contrast, SKA‐31 dose‐dependently (0.01‐5 μg bolus exposures) increased coronary flow to comparable levels in both control and diabetic rat hearts at both ages. Flow responses to sodium nitroprusside were not different between control and diabetic hearts, suggesting normal coronary smooth muscle function. Importantly, continuous exposure to a sub‐threshold concentration of SKA‐31 (i.e. 0.3 μM) did not alter basal coronary flow or heart rate, but did ameliorate the blunted BK and ADO‐evoked flow responses in diabetic hearts. In summary, these data demonstrate that SKA‐31 is an effective coronary vasodilator in a rat model of T2D exhibiting endothelial dysfunction and metabolic syndrome, and further rescues impaired vasodilatory responses to BK and ADO in the coronary circulation.Grant Funding Source: Supported by CIHR