Attenuating Action of Taurine and Labetalol on Cardiovascular Alterations by Pyridoxal-Isoproterenol, a Vitamin-Drug Interaction with Cardiopathologic Significance

Abstract

Taking into account the ability of vitamin B₆ vitamers (i.e., pyridoxal, pyridoxine, pyridoxamine) to stimulate adrenomedullary catecholamine outflow and biochemical and cardiovascular changes consistent with adrenoceptor stimulation, this study was undertaken in mice to verify the possibility that pyridoxal (PL), the most potent of the B₆ vitamers, could enter into an adverse vitamin-drug interaction when coadministered with a cardioactive drug, and that compounds like taurine (TAU) and labetalol (LAB) could be protective. To this end, mice were treated with PL (200 mg/kg) and isoproterenol (ISO 200 mg/kg), with and without a pretreatment with TAU (300 mg/kg), LAB (30 mg/kg), or TAU plus LAB, and monitored for heart rate, electrocardiographic (ECG) and myocardial electrolyte changes. PL plus ISO lowered the LD₅₀ of ISO and magnified the changes in heart rate, ECG and myocardial electrolytes seen with ISO alone. Pretreating rats with TAU or TAU plus LAB attenuated the cardiovascular changes induced by PL plus ISO to a greater extent than LAB alone. The attenuating actions of TAU and LAB probably reflect independent and complementary mechanisms of action.