CENTRAL C-TYPE NATRIURETIC PEPTIDE AUGMENTS THE HORMONE RESPONSE TO HEMORRHAGE IN CONSCIOUS SHEEP

The effect of intacerebroventricular infusions of C-type natriuretic p eptide (CNP-22, 5 mu g/h for 3 h) or vehicle on the neurohumoral respo nse of conscious sheep (n = 7) to acute moderate hemorrhage (15 ml/kg in 15 min performed I h after start of CNP) was studied. CNP alone (pr ehemorrhage) induced a transient rise (after 30 min) in heart rate (p = 0.0005), plasma aldosterone (p = 0.007), ACTH (p = 0.049), and corti sol (p = 0.049), with values returning to control levels immediately p rehemorrhage. Hemorrhage caused arterial pressure to fall (15 mmHg) an d heart rate to rise similarly on both study days. Compared with vehic le, posthemorrhage responses of AVP (p = 0.05) and cortisol (p = 0.004 ) were greater during CNP. Thus, central CNP-22 augmented the hypothal amic-pituitary-adrenal axis at baseline and in response to hemorrhage in conscious sheep.