The adrenal synthesis and tissue content of dopamine increase when the blood pressure rises in spontaneously hypertensive rats.

Hypertensive (eight-week-old) but not normotensive (four-week-old) spontaneously hypertensive rats (SHR) have a higher adrenal dopamine (DA) synthesis and release, DA concentration in adrenals and kidney and urinary excretion of DA, dihydroxyphenylacetic acid and methoxytyramine than control WKY rats. At age 14 weeks, with progressive hypertension, the heart atria and ventricle DA content also increases. These abnormalities remain unaccompanied by changes in norepinephrine and epinephrine. Increased DA release, tissue content and urinary excretion of DA and its metabolites are thus selectively involved in the sequence of events leading to hypertension in SHR.