Noradrenaline storage in deoxycorticosterone-saline hypertensive rats.

Abstract Accumulation of labeled noradrenaline ( 3 H-NA) in heart slices provided a measure of the storage ability of peripheral adrenergic nerves in rats made hypertensive by DOCA and salt (NaCl) administration. Measurements of dopamine-β-hydroxylase (DBH) and the irreversible binding of tritiated reserpine ( 3 H-R) in the heart and mesenteric arteries were taken as indices of the density of storage vesicles in nerve endings. The turnover of transmitter in peripheral adrenergic nerves was estimated by measuring the disappearance of NA after blockade of its synthesis. The storage of 3 H-NA in heart slices, measured by the retention of amine, was not changed during the development and maintenance phases of DOCA hypertension in the rat. DBH activity (31. 1 nmole of synephrine formed/g of heart and 193.7 nmole./g of mesenteric artery) and the binding of 3 H-reserpine (4.4 ng/g/heart and 4.7 ng/g of mesenteric artery) were similar to the values observed in tissues of normotensive rats. Turnover of NA was significantly accelerated in the cardiac nerves of DOCA hypertensive rats (T 1 2 6.2 h vs. 11.7 h for controls). These results show that the storage function and the density of synaptic vesicles are not changed in the peripheral adrenergic nerves of DOCA hypertensive rats. The faster disappearance of endogenous NA or exogenous labeled NA observed in vivo in hypertensive rats may be attributed to an increased release due to enhancement of nerve impulse flow, not to an impaired storage ability.