Alterations of KCl- and ATP-induced increase in [Ca2+]i in cardiomyocytes from vitamin B6 deficient rats

Although vitamin B-6 deficiency is related to coronary heart disease, no information regarding changes in myocardium due to vitamin B-6 deficiency is available in the literature. In view of the critical role played by Ca2+ in cellular function, we investigated alterations in [Ca2+](i) induced by KCI or ATP in vitamin B-6 deficient and age-matched control rats. [Ca2+](i) was measured in isolated cardiomyocytes by using the Fura-2 fluorescence technique. The KCl-induced increase in [Ca2+](i) was augmented in vitamin B-6 deficient cardiomyocytes, whereas the ATP-induced increase in [Ca2+](i) was attenuated. The specific ATP binding to sarcolemma from hearts of vitamin B-6 deficient rats was decreased. A single injection of vitamin B-6 (10 mg/kg) to vitamin B-6 deficient animals completely reversed the KCl-or ATP-induced changes in [Ca2+](i) in cardiomyocytes as well as ATP binding with sarcolemma. These results regarding altered regulation of [Ca2+](i) in cardiomyocytes and sarcolemmal ATP receptors indicate myocardial abnormalities due to vitamin B-6 deficiency.