Norepinephrine Uptake in Nerve Terminals in Hypertension-Effects of Humoral Factor and Sympathetic Activation on Norepinephrine Uptake-

点击翻译按钮获取中文摘要

Norepinephrine (NE) uptake in sympathetic nerve terminals plays an important role to regulate the concentration of NE in the sympathetic nerve cleft. In the present study, we examined the NE uptake and NE overflow in the several experimental hypertension models in rats.Young spontaneously hypertensive rats (SHR) showed the increased NE uptake and overflow from the sympathetic nerve terminals in mesenteric arterial preparation. In contrast, NE uptake and overflow were reduced in adult SHR. NE overflow was increased but NE uptake was reduced in Dahl-salt sensitive rats. In DOCA-salt hypertensive rats, NE uptake was reduced. These results suggested that NE uptake is changed by aging and play an important role in the development of hypertension in salt-dependent hypertension. NE overflow and NE uptake in synaptosomal fraction were increased in young spontaneously hypertensive rats and were reduced in adult rats. Sympathetic function in the central nervous system showed a similar trend as that in peripheral sympathetic nervous system.It has been reported that humoral factors can effect the NE uptake in the sympathetic nerve terminals. In the present study, we partially purifies Na, K^+-ATPase inhibitor from the urine of reduced renal mass hypertension and examine the effects of indigenous Na, K^+-ATPase inhibitor on NE uptake in synaptosomal fraction of hypothalamus in rats. Urine of reduced renal mass hypertension was collected and endogenous Na, K-ATPase inhibitor was separated by gel- filtration and reversed HPLC which showed digoxine-like immunoreactivity. The polarity of this substance was similar to digoxine and its molecular weight was about 400. Partially purified Na, K+-ATPase inhibitor suplressed the NE uptake in the synaptosomal fraction in dose-dependent manner in rats. These results showed that endogenous Na, K^+-ATPase inhibitor has a similar chemical characters as digoxine and a inhibitory action on NE uptake in the peripheral nerve endings.