Atrial natriuretic factor in spontaneously hypertensive rats: concentration changes with the progression of hypertension and elevated formation of cyclic GMP.

As hypertension developed in spontaneously hypertensive rats (SHR), the plasma concentration of atrial natriuretic factor (ANF) increased whereas its tissue concentration in the atria decreased. These observations suggest that ANF is secreted from the atria in response to hypertension. Atrial natriuretic factor contents in the hypothalamus and pons decreased with ageing in Wistar-Kyoto rats (WKY) but not in SHR. The responses of various SHR tissues to the hypotensive, vasorelaxant and cyclic GMP generating effects of ANF were more pronounced than in corresponding WKY tissues. The number of ANF receptors was reduced without change in the affinity in aortic smooth muscle and adrenals of SHR with established hypertension. These findings suggest that the elevated sensitivity to ANF of blood pressure of SHR can be in part explained by the increased sensitivity to ANF of guanylate cyclase in the vascular wall of SHR.