Abstract
The effects of the intranasal administration of synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) were investigated in14anesthetized spontaneously hypertensive rats (SHR; Okamoto-Aoki strain). They were given intranasally synthetic alpha-hANP in distilled water at doses of 10μg/kg, 50μg/kg and 100μg/kg. Intranasal application of 200μl of distilled water as a control was also performed in 3 anesthetized SHR. Sixteen anesthetized SHR were examined for the effects of intravenous administration of alpha-hANP at doses of 4μg/kg, 10μg/kg, 20μg/kg and 40μg/kg.
Urinary volume and the urinary excretion of sodium increased 2- to 3-fold during the 50minutes following intranasal administration of a single dose of 50μg/kg or 100μg/kg, although neither the urinary volume nor the urinary excretion of sodium increased after intranasal administration of 10μg/kg of alpha-hANP or 200μl of distilled water. There were no significant changes in arterial pressure or heart rate after the intranasal administration of synthetic alpha-hANP or distilled water. In contrast, arterial pressure was decreased and urinary volume and urinary excretion of sodium were increased, in a dose dependent manner, within 5minutes after intravenous bolus-injection of alpha-hANP and returned to their baseline levels within 20minutes.
These results indicate that intranasal administration of synthetic alpha-hANP exerts its diuretic effect without concomitant changes in arterial pressure or heart rate in SHR.
