Difference between male and female rats in cholinergic activity of parasympathetic vasodilatation in the masseter muscle.
We compared the changes in blood flow of the masseter muscle (MBF), lower lip (LBF) and common carotid artery (CCABF) evoked by electrical stimulation of the lingual nerve (LN) in order to examine whether high cholinergic activity of parasympathetic vasodilatation in females is specific for the masseter muscle, and whether sex-associated differences in cholinergic parasympathetic vasodilatation affect the regulation of blood flow to the orofacial area from the CCABF in urethane-anaesthetized, vago-sympathectomized male and female rats. Increases in the MBF, LBF and CCABF evoked by LN stimulation appear to be mediated via an activation of parasympathetic reflex vasodilatation since these increases were profoundly reduced by pretreatment with the autonomic cholinergic ganglion blocker hexamethonium (10 mg/kg). Although alpha- and beta-adrenoceptor antagonists (phentolamine and propranolol, 100 microg/kg) had no effect on the LN stimulation-induced blood flow increases in either sex, a marked difference was found between males and females in the effects of the antimuscarinic agent atropine (1-100 microg/kg) on these blood flow increases. Pretreatment with atropine slightly attenuated the increase in the MBF in males, but in females it markedly reduced the increases in all three sites measured, especially in the MBF. Our results suggest that (1) cholinergic activity of the parasympathetic vasodilatation in females is higher than that in males in most orofacial tissues, but particularly in the masseter muscle and (2) cholinergic parasympathetic vasodilatations are more involved in the regulation of blood flow to the orofacial area from the CCABF in females than in males.
Ishii
Hisayoshi
H
Division of Physiology, Department of Oral Biology, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
Niioka
Takeharu
T
Izumi
Hiroshi
H
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D017536:Carotid Artery, Common / Q000187:drug effects / Q000502:physiology; D002799:Cholinergic Fibers / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D008036:Lingual Nerve / Q000502:physiology; D008046:Lip / Q000098:blood supply / Q000187:drug effects; D008297:Male; D008406:Masseter Muscle / Q000098:blood supply* / Q000187:drug effects; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012737:Sex Factors; D013562:Sympathectomy; D012668:Trigeminal Ganglion / Q000502:physiology; D014628:Vagotomy; D014664:Vasodilation / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D005730:Ganglionic Blockers; D018727:Muscarinic Antagonists; D018738:Hexamethonium; D001285:Atropine; D011433:Propranolol; D010646:Phentolamine