Hydrogen sulfide facilitates carotid sinus baroreflex in anesthetized rats
Abstract
Aim: To study effects of hydrogen sulfide (H2S) on the carotid sinus baroreflex (CSB).
Methods: The functional curve of the carotid sinus baroreflex was measured by recording changes in arterial pressure in anesthetized male rats with perfused carotid sinus.
Results: H2S (derived from sodium hydrosulfide) at concentrations of 25, 50, and 100 mol/L facilitated the CSB, shifting the functional curve of the baroreflex downward and to the left. There was a marked increase in peak slope (PS) and reflex decrease in blood pressure (RD). Effects were concentration-dependent. Pretreatment with glibenclamide (20 mol/L), a KATP channel blocker, abolished the above effects of H2S on CSB. Pretreatment with Bay K8644 (an agonist of calcium channels; 500 mol/L) eliminated the effect of H2S on CSB. An inhibitor of cystathionine -lyase (CSE), DL-propargylglycine (PPG; 200 mol/L), inhibited CSB in male rats and shifted the functional curve of the baroreflex upward and to the right.
Conclusion: These data suggest that exogenous H2S exerts a facilitatory role on isolated CSB through opening KATP channels and further closing the calcium channels in vascular smooth muscle. Endogenous H2S may activate the activity of the CSB in vivo.
Keywords:
Methods: The functional curve of the carotid sinus baroreflex was measured by recording changes in arterial pressure in anesthetized male rats with perfused carotid sinus.
Results: H2S (derived from sodium hydrosulfide) at concentrations of 25, 50, and 100 mol/L facilitated the CSB, shifting the functional curve of the baroreflex downward and to the left. There was a marked increase in peak slope (PS) and reflex decrease in blood pressure (RD). Effects were concentration-dependent. Pretreatment with glibenclamide (20 mol/L), a KATP channel blocker, abolished the above effects of H2S on CSB. Pretreatment with Bay K8644 (an agonist of calcium channels; 500 mol/L) eliminated the effect of H2S on CSB. An inhibitor of cystathionine -lyase (CSE), DL-propargylglycine (PPG; 200 mol/L), inhibited CSB in male rats and shifted the functional curve of the baroreflex upward and to the right.
Conclusion: These data suggest that exogenous H2S exerts a facilitatory role on isolated CSB through opening KATP channels and further closing the calcium channels in vascular smooth muscle. Endogenous H2S may activate the activity of the CSB in vivo.