Adrenergic modulation of neurogenic vasodilation in the rat mesenteric resistance blood vessel

• Published in: Japanese Journal of Pharmacology 1989, Vol.49 (suppl), p.104-104
• Main Authors: Kawasaki, Hiromu, Muki, Chikako, Takasaki, Koichiro
• Format: Article
• Language: English
• ISSN: 0021-5198; 1347-3506
• DOI: 10.1016/S0021-5198(19)56155-8

The previous report suggested that circulating norepinephrine (NE) may modulate the neurogenic vasodilation of the mesenteric resistance blood vessel, which is mediated by nonadrenergic, noncholinergic (NANC) nerves (Nature, 1988). The present study was designed to study the modulation of neuronally released NE in the neurogenic vasodilation of the rat mesenteric resistance vessel. The mesenteric vascular beds isolated from male Wistar rats were perfused with Krebs solution at a constant flow rate of 5 ml/min. Changes in perfusion pressure were measured with a pressure transducer. In the preparation contracted by continuous perfusion of 3 nM endothelin, periarterial nerve stimulation (PNS; 2, 4, 8 Hz) caused little or a slight vasodilation in the presence of prazosin (50 nM) which was added to block postsynaptically adrenergic vasocontraction. However, when guanethidine (5 μM) was added to block adrenergic neurotransmission, PNS produced a marked vasodilation even in the presence of prazosin. Furthermore, marked vasodilator responses to PNS were produced in the combined presence of prazosin and yohimbine (1 μM). These results suggest that NE released from vascular adrenergic nerves regulates the neurogenic vasodilation mediated by NANC nerves, probably inhibiting a vasodilator transmitter release through activation of alpha-2 adrenoceptors on NANC nerves.