Resting Levels and Baroreflex Control of Cardiac and Renal Sympathetic Nerve Activity in Heart Failure

Abstract

During heart failure (HF), cardiac noradrenaline release is increased by up to 50‐fold, a much greater increase than from other organs. The reasons behind this preferential activation of cardiac sympathetic nerve activity (SNA) remain unclear. We hypothesised that the basal level of cardiac SNA in normal animals is set at a lower percentage of its maximum than is SNA to other organs. To investigate this possibility we measured cardiac SNA and renal SNA simultaneously in conscious sheep, at least 4 days after surgery. Experiments were conducted in normal (n = 7) and HF animals (n = 7). Consistent with our hypothesis, the burst frequency of cardiac SNA was significantly lower than renal SNA in..