Growth hormone in cardiac hypertrophy induced by nephrogenous hypertension.

Current evidence about the role of growth hormone in cardiac hypertrophy is ambiguous. The purpose of this investigation was to determine whether growth hormone was an important element in the cardiac hypertrophy induced by systemic hypertension. Male rats with either an intact hypophysis or a hypophysectomy were bilaterally adrenalectomized, and corticoids were replaced with exogenous deoxycorticosterone and hydrocortosone. Hypophysectomized rats were further treated with thyroxine, testosterone, and, where appropriate, bovine growth hormone. Selected groups of rats were made hypertensive by means of a surgical compression of the renal capsule which produced systemic hypertension. The magnitude of the hypertension was measured in awake rats by means of a tail plethysmograph and compressing tail-cuff. The hormone replacement program re-established systolic blood pressures in sham-operated, hypophysectomized rats to levels observed in intact-hypophysis, sham-operated rats. Thus, hypertensive, hypophysectomized rats obtained pressures above both hypophysectomized and intact-hypophysis, sham-operated rats. Hypertensive rats with an intact hypophysis and hypophysectomized rats with growth hormone developed cardiac hypertrophy. In spite of the hormone therapy, the above normal systemic blood pressures, and low mortality hopophysectomized rats without growth hormone did not develop cardiac hypertrophy.