Effects of neurotensin on norepinephrine release in blood vessels of spontaneously hypertensive rats.
The present study was performed to investigate the effects of neurotensin on noradrenergic transmission in blood vessels of hypertension. In the perfused mesenteric vasculatures prepared from spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats, we examined the influences of neurotensin on vascular responsiveness and norepinephrine release from adrenergic neurons. In studies with male standard Wistar rats, endogenous norepinephrine release during periarterial nerve stimulation was inhibited by neurotensin in a dose-dependent manner. Vasoconstrictor responses to electrical nerve stimulation were also inhibited by neurotensin. In SHR, the stimulation-evoked pressor responses and norepinephrine release were enhanced compared with WKY rats. The suppression of these responses by neurotensin was significantly less in SHR than in WKY rats. These results show that neurotensin could have a modulatory effect on noradrenergic activity and cause a decrease in stimulation-evoked norepinephrine release from vascular adrenergic neurons. The lesser reduction of pressor responses and norepinephrine release by neurotensin in SHR might suggest an insufficient regulation of vascular adrenergic transmission by the peptide hormone in hypertension.
Tsuda
K
K
Department of Medicine, Wakayama Medical College, Japan.
Masuyama
Y
Y
D000320:Adrenergic Fibers / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001808:Blood Vessels / Q000294:innervation / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008643:Mesentery / Q000294:innervation / Q000378:metabolism / Q000502:physiology; D009496:Neurotensin / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects
D009496:Neurotensin; D009638:Norepinephrine