Lymphatic transport rate of noradrenaline during adrenergic thermogenesis

The lymphatic concentration of noradrenaline (NA) and lymph flow in the thoracic duct of cold-acclimated rats were measured under conditions of the quasi-stationary thermogenic response to i.v. infused NA. Both parameters increased linearly with increased rate of NA infusion. The lymphatic transport rate of NA is quadratically related to the infusion rate which indicates the same relation for the efflux of NA from blood into the extravascular space. This non-linear efflux of NA causes a non-linear thermogenic response to NA.     

Prostaglandins--modulation of adrenergic nervous system.

Prostaglandins (PGs) affect vascular tone by a direct action on the vascular smooth muscle and by influencing vascular reactivity to adrenergic simuli and several vasoactive substances. Thus, in the isolated Tyrode's perfused rabbit renal, mesenteric and splenic vasculature PGE2 inhibited adrenergically induced vasoconstriction. Since the vasoconstrictor responses to renal nerve stimulation were enhanced by the blockade of PG synthesis and were reduced by stimulation of PG synthesis with arachidonic acid, this suggests that PGE2 functions as an inhibitory modulator of the adrenergic nervous system. However, our demonstration that PGE2 enhanced adrenergically induced vasoconstriction in the renal and mesenteric vasculature of the rat, but had opposite effects in the rat splenic vasculature indicates that the modulatory-effect of PGE-compounds on the adrenergic neuromuscular junction is species dependent and varies in different vascular beds within the same species. Prostaglandins, the release of which is evoked by several vasoactive substances including angiotensins, kinins, and adenine nucleotides, may also contribute to the regulation of vascular tone by either opposing or amplifying the vascular actions of vasoactive substances.     

Influence of adrenergic nervous and prostaglandin systems on hydralazine-induced renin release

The role of the beta-adrenergic nervous and prostaglandin systems in vasodilator-induced activation of the renin-angiotensin system was studied in conscious rats. The plasma renin activity (PRA) response to intravenous hydralazine (0.25, 0.5 and 1 mg/kg body wt.) was compared to the PRA response following administration of similar doses of hydralazine to rats pretreated with either indomethacin (3 mg/kg body wt. i.v.) or indomethacin and propranolol (1 mg/kg body wt. i.v.). PRA increased significantly above control levels after each of the hydralazine doses. In rats pretreated with indomethacin, PRA did not increase with the 0.25 mg/kg dose of hydralazine; increased significantly with the 0.5 mg/kg dose but remained significantly lower than the PRA response in the absence of indomethacin; and increased with the 1 mg/kg dose to a level not significantly different from PRA in rats receiving only hydralazine. When rats were pretreated with indomethacin and propranolol, PRA did not increase significantly in response to either the 0.25 or 0.5 mg/kg doses of hydralazine. Although a statistically significant increase in PRA was noted with the 1 mg/kg dose of hydralazine, the level of PRA achieved was very low and only 15% of that observed with the other two treatment regimens (i.e., hydralazine alone or indomethacin and hydralazine). These results demonstrate that vasodilator-induced renin release is only partially mediated via the prostaglandin system, that the degree of this control is related to the intensity of vasodilator stimulus and that renin release following administration of hydralazine can be attributed almost entirely to activation of the beta-adrenergic nervous and prostaglandin systems.     

中枢神经系统去甲肾上腺素分泌的实时检测

为了探讨与中枢神经系统单胺类递质分泌失调有关疾病的中枢机制,人们对单胺类递质分泌动力学的研究越来越有兴趣。去甲肾上腺素是中枢神经系统重要的递质和调质,本文介绍了我们实验室最近发展的实时检测中枢神经系统去甲肾上腺素分泌的一些技术方法,并比较了电化学微碳纤电极（carbon fiber electrode,CFE）测量与电生理、荧光显微测量技术优缺点,阐述了CFE技术在神经科学研究中的一个基本应用。