Atrial natriuretic factor gene expression in rat ventricle during experimental hypertension

Abstract

Activation of atrial natriuretic factor (ANF) gene expression has been reported in the rat ventricle in several models of hemodynamic overload, including hypertension. However, nothing is known about the potential trigger(s) and the time course of this activation during the development of hypertension. We measured aortic blood pressure, left ventricular hypertrophy (LVH), and left ventricular ANF mRNA concentration (LV ANF mRNA) in a first group of rats (study A) killed at 5 and 18 h and 2, 4, 6, 9, 15, and 30 days after suprarenal coarctation of the abdominal aorta. Coarctation induced a progressive rise in aortic blood pressure and left ventricular mass. We observed a biphasic accumulation of ANF mRNA in the left ventricle with a peak at day 4 averaging 20 times the control value long before stable hypertension and hypertrophy were achieved, followed by a decrease until day 9. This decrease was followed by a new rise, which stabilized around 10 times the control value seen during stable hypertension and hypertrophy. In a second group of rats killed at days 4 and 30 (study B), we determined, in addition to the previous parameters, left ventricular end-diastolic pressure (LVEDP), plasma renin (PRC), and plasma ANF concentrations. LVEDP and PRC were markedly increased at day 4, but at day 30, during stable hypertension and hypertrophy, these parameters returned to control values, whereas plasma ANF was increased. Using immunocytochemistry, we looked in a third group of rats (study C) for the presence of the immunoreactive peptide at days 4 and 30.(ABSTRACT TRUNCATED AT 250 WORDS)