Hydrogen sulfide facilitates carotid sinus baroreceptor activity in anesthetized male rats.
BACKGROUND
It has been reported that hydrogen sulfide (H(2)S) could relax vascular smooth muscle by direct activation of K(ATP) channels and hyperpolarization of the membrane potential. Recently, our study has shown that H(2)S facilitated carotid baroreflex. This study was conducted to investigate the effect of H(2)S on carotid baroreceptor activity (CBA).


METHODS
The functional curve of carotid baroreceptor (FCCB) was constructed and the functional parameters of carotid baroreceptor were measured by recording sinus nerve afferent discharge in anesthetized male rats with perfused isolated carotid sinus.


RESULTS
H(2)S (derived from NaHS) 25, 50 and 100 micromol/L facilitated CBA, which shifted FCCB to the left and upward. There was a marked increase in peak slope (PS) and peak integral value of carotid sinus nerve charge (PIV) in a concentration-dependent manner. Pretreatment with glibenclamide (20 micromol/L), a K(ATP) channel blocker, the above effects of H(2)S on CBA were abolished. Pretreatment with Bay K8644 (an agonist of calcium channels, 500 nmol/L) eliminated the role of H(2)S on CBA. An inhibitor of cystathionine gamma-lyase (CSE), DL-propargylglycine (PPG, 200 micromol/L) inhibited CBA in male rats and shifted FCCB to the right and downward.


CONCLUSIONS
Our results suggest that exogenous H(2)S exerts a facilitatory role on isolated CBA through opening K(ATP) channels and further closing the calcium channels in vascular smooth muscle. Endogenous H(2)S may activate CBA in vivo.
Xiao
Lin
L
Department of Physiology, Institute of Basic Medicine, Hebei Medical Univesity, Shijiazhuang 050017, China.
Wu
Yu-ming
YM
Wang
Ru
R
Liu
Yi-xian
YX
Wang
Fu-wei
FW
He
Rui-rong
RR
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000480:Alkynes / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D002346:Carotid Sinus / Q000187:drug effects* / Q000502:physiology; D005905:Glyburide / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D008297:Male; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000480:Alkynes; C009055:propargylglycine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D005905:Glyburide; D005998:Glycine; D006862:Hydrogen Sulfide