Role of hydrogen sulfide in ventilatory responses to hypercapnia in the medullary raphe of adult rats.

New Findings: What is the central question of this study? There is evidence that H S plays a role in the control of breathing: what are its actions on the ventilatory and thermoregulatory responses to hypercapnia via effects in the medullary raphe, a brainstem region that participates in the ventilatory adjustments to hypercapnia? What is the main finding and its importance? Hypercapnia increased the endogenous production of H S in the medullary raphe. Inhibition of endogenous H S attenuated the ventilatory response to hypercapnia in unanaesthetized rats, suggesting its excitatory action via the cystathionine β-synthase-H S pathway in the medullary raphe.

Abstract: Hydrogen sulfide (H S) has been recently recognized as a gasotransmitter alongside carbon monoxide (CO) and nitric oxide (NO).

Cigarette smoke exposure causes systemic and autonomic cardiocirculatory changes in rats depending on the daily exposure dose.

Aims: To evaluate the systemic changes and autonomic cardiocirculatory control of awaken rats chronically exposed to the cigarette smoke (CS) of 1 or 2 cigarettes/day.

Main Methods: Rats were exposed to clean air (control) or cigarette smoke of 1 (CS1) or 2 (CS2) cigarettes/animal/day for 30 days. Then, arterial pressure (AP) and heart rate (HR) were recorded in conscious rats to assess spontaneous baroreflex sensitivity and HR and AP variabilities.