Deficient dopamine metabolism in the celiac ganglion of spontaneously hypertensive rats.

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Abstract
Dopamine (DA), in the small intensely fluorescent (SIF) cells of a sympathetic ganglion, was shown to release on to sympathetic neurons with preganglionic cholinergic stimulation. DA suppresses transmission in sympathetic ganglia. The concentration of 3,4-dihydroxyphenylacetic acid (DOPAC) within the ganglion is a relative measure of DA release and metabolism. DA, norepinephrine (NE), and DOPAC in the celiac ganglia of spontaneously hypertensive rats (SHR) were assayed during the development of hypertension, and in control Wistar-Kyoto rats (WKR). Blood pressure began to rise in SHR after age 4-6 wk and became stable after .apprx. 10 wk. In WKR, DOPAC concentrations were highest in the ganglion at 4 wk, and declined by .apprx. 45% at 6 wk to levels where they remained for 20 wk. DOPAC concentrations in SHR were lowest in the ganglion at 4 wk, increased in parallel to blood pressure, and at 20 wk were comparable to the concentration in WKR. Sectioning the greater splanchnic nerves did not induce major changes in the content of NE and DA in the celiac ganglion but strikingly reduced DOPAC concentrations in SHR and WKR. DA conversion to DOPAC may be modulated by preganglionic cholinergic neuronal activity. Sectioning the nerves in SHR delayed development of hypertension but did not significantly alter blood pressure in WKR. Young SHR are probably not able to modulate the sensitivity of sympathetic neurons to incoming cholinergic activity to the celiac ganglion because of a deficiency in SIF cell DA metabolism, and the consequences may be important in the development of hypertension.