Effect of isoproterenol and taurine on heart calcium in normal and cardiomyopathic hamsters

Calcium accumulation has been implicated in the cardiac necrosis induced by isoproterenol and in the development of the cardiomyopathy in the BIO 14.6 hamster. Taurine, a natural constituent of the heart, has been shown to exert a modulating effect on calcium levels in the heart. Heart calcium and taurine levels were determined in BIO 14.6 and random bred (F₁B) hamsters treated with isoproterenol (80 mg/kg) following a 60 day drinking regimen of either taurine (100 mmol/l) or guanidinoethyl sulfonate (1%). Taurine supplementation provided some protection for the random bred hamster heart against isoproterenol induced calcium accumulation, but that protection was not demonstrable in the BIO 14.6 strain despite an elevated heart taurine content. The feeding of guanidinoethyl sulfonate decreased the taurine content of the heart in both strains, but guanidinoethyl sulfonate was unable to block taurine elevation following isoproterenol treatment in either strain. Since taurine feeding retards the usual calcium accumulation in the BIO 14.6, but is without statistically significant effect on the additional calcium accumulation induced by isoproterenol, the protecitive action of taurine seems insufficient to counteract the combined effect of isoproterenol and the myopathic process.