Pacing-induced heart failure in rabbits enhanced carotid body chemoreceptor activity and reduced nitric oxide production compared to sham rabbits (P<0.05).
Does impaired nitric oxide production contribute to enhanced carotid body chemoreceptor activity in a rabbit model of heart failure?
In a rabbit model of pacing-induced heart failure, impaired nitric oxide production in the carotid body contributes to enhanced peripheral chemoreflex activity.
p-value: p=<0.05
An enhanced peripheral chemoreflex has been documented in patients with chronic heart failure (CHF). This study aimed to examine the characteristics of carotid body (CB) chemoreceptors in response to isocapnic hypoxia in a rabbit model of pacing-induced CHF and to evaluate the possible role that nitric oxide (NO) plays in the altered characteristics. The chemosensitive characteristics of the CB were evaluated by recording single-unit activity from the carotid sinus nerve in both an intact and a vascularly isolated preparation. It was found that the baseline discharge under normoxia (intact preparation: arterial PO2 90-95 Torr; isolated preparation: PO2 100-110 Torr) and the chemosensitivity in response to graded hypoxia (PO2 40-70 Torr) were enhanced in CHF vs. sham rabbits. These alterations were independent of the CB preparations (intact vs. isolated). NO synthase inhibition by Nomega-nitro-L-arginine increased the baseline discharge and the chemosensitivity in the intact preparation, whereas L-arginine (10(-5) M) inhibited the baseline discharge and the chemosensitivity in the isolated preparation in sham but not in CHF rabbits. S-nitroso-N-acetylpenicillamine, an NO donor, inhibited the baseline discharge and the chemosensitivity in both CB preparations in CHF rabbits but only in the isolated preparation in sham rabbits. The amount of NO produced in vitro by the CB under normoxia was less in CHF rabbits than in sham rabbits (P < 0.05). NO synthase-positive varicosities of nerve fibers within the CB were less in CHF rabbits than in sham rabbits (P < 0.05). These data indicate that an enhanced input from CB occurs in the rabbit model of pacing-induced CHF and that an impairment of NO production may contribute to this alteration.
Sun et al. (Thu,) conducted a other in chronic heart failure. Pacing-induced chronic heart failure vs. Sham rabbits was evaluated on Carotid body baseline discharge, chemosensitivity, and nitric oxide production (p=<0.05). Pacing-induced heart failure in rabbits enhanced carotid body chemoreceptor activity and reduced nitric oxide production compared to sham rabbits (P<0.05).