Capsaicin facilitates carotid sinus baroreflex in anesthetized rats.
The effects of capsaicin (CAP) on the carotid sinus baroreflex were studied in 30 anaesthetized rats with perfused isolated carotid sinus. The results are as follows. (1) By perfusing the isolated carotid sinus with CAP (1 micromol/L), the functional curve of the baroreflex was shifted to the left and downward, with a peak slope (PS) increasing from 0.34+/-0.01 to 0.42+/-0.01 (P<0.01), whereas the reflex decrease (RD) in mean arterial pressure was enhanced from 36.51+/-1.26 to 45.01+/-0.71 mmHg (P<0.01). Meanwhile, the threshold pressure, equilibrium pressure and saturation pressure were all significantly decreased from 70.43 +/-2.09 to 52.86 +/-2.80 mmHg (P<0.01), 95.5+/-1.71 to 87.00+/-1.58 mmHg (P<0.01) and 177.60+/-1.37 to 163.55+/-2.12 mmHg (P<0.01), respectively. Among the functional parameters of carotid baroreflex, the changes in PS and RD induced by capsaicin were dose-dependent. (2) By pretreatment with ruthenium red (RR, 100 micromol/L), an antagonist of vanilloid receptor subtype 1 (VR(1)), the above effects of CAP on carotid baroreflex were abolished. (3) The CAP-induced change in the baroreflex was also eliminated by pretreatment with glibenclamide (20 microm ol/L), a K(ATP) channel blocker. On the basis of the results, it is concluded that CAP facilitates the carotid baroreflex, an effect of which may be resulted from the opening of K(ATP) channels mediated by VR(1).
Zhang
Hao
H
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017 China.
Liu
Yi-Xian
YX
Wu
Yu-Ming
YM
Wang
Sheng
S
He
Rui-Rong
RR
D000818:Animals; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D002211:Capsaicin / Q000494:pharmacology*; D002346:Carotid Sinus / Q000187:drug effects / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000037:antagonists & inhibitors; D012430:Ruthenium Red / Q000494:pharmacology; D050916:TRPV Cation Channels
D026902:Potassium Channel Blockers; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D012430:Ruthenium Red; D002211:Capsaicin; D005905:Glyburide