Quantitative and sustained suppression of renal sympathetic nerve activity by left atrial distension in conscious dogs.

In order to investigate the interrelations between left atrial pressure (Pla) and renal sympathetic nerve activity (RSNA) and heart rate (HR), Pla was increased by a balloon both in conscious sham-operated and cardiac-denervated dogs. RSNA was decreased and HR was increased with increasign Pla in sham-operated dogs. The reflex changes in RSNA and HR induced by the stimulation of atrial receptors persisted for at least 15 min. There was a consistent relationship between Pla and RSNA which could be described by a single exponential equation: % delta RSNA = -80.0(1-e-0.395 delta Pla), or by a linear equation when delta Pla was less than 6 mmHg; % delta RSNA = -13.5 delta Pla-2.25. The relationship between Pla and HR can be described by a single exponential equation: delta HR = 86.5(1-e-0.125 delta Pla). A significant linear relationship between RSNA and HR was obtained during a graded left atrial distention (% delta RSNA = -1.08 delta HR-17.7). In cardiac-denervated dogs, RSNA tended to increase and HR remained constant during the left atrial distention. These results indicate that left atrial receptors regulate RSNA and HR in both a quantitative and sustained manner in conscious sham-operated dogs.