EFFECTS OF RESERPINE ON THE ADRENAL MEDULLA OF THE SPONTANEOUSLY HYPERTENSIVE RAT

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Abstract
1 Reserpine administration resulted in a larger initial decline in adrenal catecholamines in spontaneously hypertensive rats (SHR) than in normotensive Wistar rats (NWR); the difference was eliminated by pretreatment with chlorisondamine. 2 Reserpine also produced a larger increase in SHR catecholamines and dopamine β-hydroxylase several days later; chlorisondamine pretreatment did not prevent the increases, although it did slightly slow the increases. 3 Vesicles from SHR or NWR incubated with reserpine in vitro demonstrated equivalent inhibition of adenosine 5′-triphosphate (ATP)-Mg2+ -stimulated adrenaline uptake. 4 Recovery of uptake was more rapid in SHR than in NWR after reserpine inhibition, and this was associated with a burst of new vesicle synthesis in the SHR; chlorisondamine pretreatment reduced the number of new, immature vesicles in reserpine-treated SHR. 5 Both SHR and NWR secreted equal proportions of their adrenal catecholamine contents after nicotine administration. 6 These data suggest that the sympatho-adrenal system of the SHR exhibits an enhanced reflex response to reserpine but that reserpine is equally effective in SHR and NWR in producing blockade of vesicular catecholamine transport; these alterations can affect markedly the actions of autonomic drugs in the SHR.