Cardiovascular responses to salt-loading in conscious domestic geese

1. The intravenous injection of large volumes of 0.5 M-NaCl that are usually used to induce nasal gland secretion in marine birds has been shown in geese to increase greatly plasma volume, cardiac output, heart rate and stroke volume at the time secretion commences after 2-8 min.2. There were no consistent changes in mean arterial blood pressure or in the distribution of the cardiac output to major organs except to the salt-glands whose share increased approximately fourteenfold. Salt-gland blood flow remained high for 10-20 min after cardiac output and heart rate had returned to nearly normal levels.3. The increases in plasma volume and venous return are unlikely to be the stimuli for salt-gland secretion because secretion was also initiated by giving artificial sea water into the proventriculus and this produced no changes in these variables at the time secretion commenced, 5-14 min later.4. At the start of secretion in orally loaded birds, the only detectable changes in the plasma were small increases in osmolality (from 1.3 to 4.6%), Na (from 0.3 to 6%) and Cl (from 1.3 to 7.1%) concentrations.