Primary afferent nerves mediate in part beta-adrenoceptor stimulation-induced mesenteric hyperemia in rats.
We tested the hypothesis that in the rat duodenum and intestine the mesenteric hyperemia due to beta-adrenoceptor stimulation is mediated by capsaicin-sensitive afferent nerves. Superior mesenteric artery blood flow was measured by pulsed Doppler flowmetry in the anesthetized rat. Functional ablation of afferent nerves was accomplished by subcutaneous 125 mg/kg capsaicin pretreatment 10 to 14 days before blood flow studies. Blockade of capsaicin-sensitive cation-selective ion channels of the duodenal and intestinal mucosal afferent nerves was achieved by intraduodenal 0.1% ruthenium red given 15 min prior to the intraduodenal administration of 5 mg/kg isoproterenol. Functional ablation of the afferent nerves and blockade of the capsaicin-sensitive cation-selective ion channels alone or in combination resulted in a significant reduction of mesenteric hyperemia induced by intraduodenal isoproterenol. These data support the hypothesis that beta-adrenoceptor stimulation by intraduodenal isoproterenol induces mesenteric hyperemia in part through afferent nerves in the rat duodenal and intestinal mucosa. The results suggest for the first time a link between beta-adrenoceptor function and peripheral capsaicin-sensitive afferent nerve-mediated mechanism in the rat gut.
Seno
K
K
Research Service, Sepulveda Veterans Administration Medical Center, California 91343, USA.
Lam
K
K
Leung
J W
JW
Leung
F W
FW
D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D003714:Denervation; D004386:Duodenum / Q000187:drug effects / Q000294:innervation; D006940:Hyperemia / Q000209:etiology* / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000294:innervation; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D017538:Mesenteric Artery, Superior / Q000187:drug effects / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*
D011943:Receptors, Adrenergic, beta; D007545:Isoproterenol; D002211:Capsaicin