악하선 분비와 선혈류에 미치는 L-NAME와 Glyburide의 영향

Effects of L-Name and Glyburide on the salivary scrtion and vasodilation in the submandibular gland of the cat

The present study was designed to investigate whether and to what extent endothelium-derived nitric oxide (EDNO) and endothelium-derived hyperpolarizing factor (EDHF) are involed in vasodilation and salivation induced by parasympathetic stimulation. Effects of Nw-notro-L-arginine-methyl ester (L-NAME), which blocks the synthesis of EDNO from L-arginine, and glyburide, which blocks ATP-sensitive K+ channel (KATP), on vasodilation and salivation induced by chorda stimulation or administration of various vasodilators in the submandibular gland was examined in anesthetized cats. Effects of L-NAME and glyburide on K+ efflux induced by carbachol was also examined using the excised submaxillary slice. 1. Salivary secretion in response to the chorda stimulation (1-20 Hz) was completely blocked by treament with atropine (1 mg/kg). Increased blood flow response to the chorda stimulation was significantly attenuated when low frequency (1, 2, 5 Hz)-stimuli were applied, while that to a higher frequency (10, 20 Hz)-stimuli were not affected. 2. Intra-arterial infusion of L-NAME (100mg/kg) or glyburide (2 mg/kg) significantly diminished the vasodilatory and salivary responses to the chorda stimulation regardless of the stimuli frequencies used. 3. Intra-arterial infusion of L-NAME (100 mg/kg) or methylene blue (2 mg/kg) markedly diminished the vasodilatory responses to acetylcholine (5μg/kg), vasoactive intestinal peptide (5μg/kg) or bradykinin (5μg/kg). 4. The vasodilator responses to the ACh, VIP, or BK (5μg/kg) was significantly attenuated by intra-arterial infusion of glyburide (2 mg/kg). 5. In the excised submandibular slice, K+ efflux in response to carbarchol (10E-5mol/L) was significantly attenuated by pretreatment with glyburide (10E-5 mol/L) diminished, although transiently, the K+ efflux. 6. In the isolated submaxillary artery precontracted with phenylephrine (10E-5 mol/L), the vasorelaxation induced by ACh (10E-7 mol/L), was reversed by methylene blue and BaCl₂ (10E-6 mol/L). These results suggest that EDNO and EDHF are implicated in the parasympathetic vasodilation and salivary secretion in the submandibular gland.