Role of substance P and neurotensin in the regulation of neurosecretion and vascular responsiveness in hypertension.
The purpose of the present study was to investigate the effects of vasoactive neuropeptides, such as substance P or neurotensin, on vascular adrenergic neurotransmission in hypertension. In perfused mesenteric vasculatures prepared from spontaneously hypertensive rats (SHR), we examined the effects of substance P and neurotensin on vascular responsiveness and noradrenaline release from the sympathetic nerve endings. Stimulation-evoked noradrenaline release and pressor responses were inhibited by substance P and neurotensin. In SHR, the noradrenaline release and pressor responses during electrical nerve stimulation were significantly greater than in Wistar-Kyoto rats (WKY). The inhibitory effects of these responses by substance P and neurotensin were attenuated in SHR compared with WKY. These results showed that substance P and neurotensin could affect the presynaptic site of the blood vessels and cause a decrease in electrically stimulated noradrenaline release from the vascular adrenergic neurons. The reduction of noradrenaline release and pressor responses by substance P and neurotensin in SHR might suggest insufficient regulation of the vascular adrenergic transmission by these vasoactive peptides in hypertension.
Tsuda
K
K
Department of Medicine, Wakayama Medical College, Japan.
Shima
H
H
Ura
M
M
Takeda
J
J
Kimura
K
K
Nishio
I
I
Masuyama
Y
Y
D000818:Animals; D004558:Electric Stimulation; D006973:Hypertension / Q000503:physiopathology*; D008643:Mesentery / Q000098:blood supply; D009496:Neurotensin / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000502:physiology*; D014666:Vasomotor System / Q000502:physiology
D013373:Substance P; D009496:Neurotensin; D009638:Norepinephrine