Pathogenesis of hypertension in spontaneously hypertensive rats: definite evidence against a pressor role of vasopressin.

A number of experiments were performed in order to investigate the possible importance of vasopressin (AVP) in the pathogenesis of high blood pressure in spontaneously hypertensive rats of the stroke prone strain (SHRSP). Radioimmunological studies revealed reduced concentrations of AVP in the plasma and brain of SHRSP as compared to normotensive controls. Intravenous administration of an AVP pressor antagonist had no significant influence on mean arterial blood pressure, cardiac output and total peripheral resistance in SHRSP. Crossbreeding of SHRSP with rats homozygous for hypothalamic diabetes insipidus resulted in the development of a new strain of rats which show high blood pressure despite of a complete lack in AVP. These results argue strongly against a pressor role of AVP in the development or maintenance of hypertension in SHRSP.