Thioglycine and l-thiovaline are stable under acidic and basic conditions but in the presence of bicarbonate they liberate the gasotransmitter H(2)S. In cells both thioamino acids were proven to enhance cGMP formation and promote vasorelaxation in mouse aortic rings. Given that H(2)S is known to lower arterial hypertension, reduce oxidative stress and exhibit cardioprotective effects in preclinical models, H(2)S donors hold promise as novel treatments for cardiovascular diseases.