Effects of atrial natriuretic peptide on the sarcolemmal Na-K pump in rabbit myocytes

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The sodium pump transports sodium ions across cell membranes from the inside of cells to the outside. This maintains the concentration of sodium more than ten-fold lower on the inside than the outside. This transmembrane concentration gradient is essential for normal cell function. It is well established that the sodium pump is regulated by a variety of hormones. In a pilot study we have demonstrated that a hormone secreted by the heart, atrial natriuretic peptide, stimulates the sodium pump in single heart cells. This has not been reported previously. This study will examine the cellular mechanisms that mediate the stimulation of the sodium pump by atrial natriuretic peptide. A study on the effect of atrial natriuretic peptide on the regulation of sodium in heart cells is particularly important from the perspective of heart failure, a condition characterised by an inability of the heart to pump a sufficient amount of blood. While the underlying causes of heart failure vary widely activation of several hormone systems is a common feature regardless of the aetiology. It has already been well established in clinical practice that interfering with hormone activation by drugs improves symptoms as well as survival. Drugs have recently been developed that can increase levels of atrial natriuretic peptide. Since raised levels of sodium may contribute to important heart cell abnormalities in heart failure the effect of atrial natriuretic peptide on sodium export from the cells by the pump may have important implications for treatment of this serious and common condition.