Effects of isoflurane on parasympathetic vasodilatation in the rat submandibular gland.
Volatile anesthetics have been known to suppress parasympathetic reflex vasodilatation in the lower lip and palate. However, in the submandibular gland, little is known about the effects of these anesthetics on the parasympathetic vasodilatation elicited by reflex and direct (i.e., non-reflex) activation of the parasympathetic vasodilator mechanisms. Although both parasympathetic vasodilatations were inhibited by isoflurane in a concentration- and time-dependent manner, the effects of continuous administration of the alpha(1)-adrenoceptor agonist methoxamine were markedly different: The reflex vasodilatation was not affected by methoxamine, while the direct vasodilatation was significantly reduced. Picrotoxin (GABA(A) receptor antagonist) attenuated the inhibitory effect of isoflurane on direct vasodilatation and the systemic arterial blood pressure. These findings suggest that the isoflurane-induced inhibitory effects on direct vasodilatation are produced by a decrease of peripheral vascular tone by GABAergic mechanisms, whereas those on the reflex vasodilatation are produced exclusively by the inhibition of the reflex center.
Division of Dento-Oral Anesthesiology, Tohoku University Graduate School of Dentistry, Aoba, Sendai, 980-8575, Japan.
K
K
Mizuta
F
F
Mizuta
M
M
Takahashi
H
H
Ishii
T
T
Niioka
H
H
Izumi
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002814:Chorda Tympani Nerve / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D007530:Isoflurane / Q000494:pharmacology*; D008036:Lingual Nerve / Q000187:drug effects / Q000502:physiology; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D017777:Parasympathetic Fibers, Postganglionic / Q000187:drug effects*; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects; D013363:Submandibular Gland / Q000098:blood supply* / Q000187:drug effects* / Q000294:innervation; D013566:Sympathomimetics / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D013566:Sympathomimetics; D007530:Isoflurane; D008729:Methoxamine