Prolonged hemodynamic effects of intermittent, brief chemoreceptor stimulation in humans.

Abstract

Augmented arterial chemoreceptor reflex tonic drive was observed in human subjects with essential mild hypertension and it was suggested as a sympatho-excitatory mechanism contributing to elevated blood pressure (Trzebski et al, 1982; Trzebski, 1992). Human subjects are exposed to repetitive episodic nocturnal hypoxic chemoreceptor stimulation in obturative sleep apnea syndrome (OSAS). In agreement with the original hypothesis on the role of the chemoreceptor reflex in hypertension, OSAS is usually accompanied by systemic arterial hypertension (Jeong et al, 1989; Hla et al, 1994) which is reversed by tracheostomy (Guilleminault et al, 1981). Repetitive, brief hypoxia produces in rats a sustained blood pressure elevation (Fletcher et al, 1992a) prevented by carotid chemoreceptor or sympathetic denervation (Fletcher et al, 1992b,c). In contrast to baroreceptors, chemoreceptors do not exhibit adaptation with long-lasting stimulation. On the contrary, their responsiveness appears to be enhanced with prolonged hypoxia (Smith et al, 1986; Barnard et al, 1987; Vizek et al, 1987; Nielsen et al, 1988; but Tatsumi, 1991). In awake OSAS patients resting sympathetic vasoconstrictor activity is augmented (Carlson et al, 1993). Morgan et al (1995) found long-lasting vasoconstrictor sympathetic activation in healthy human subjects after termination of a 20 min period of combined hypoxia and hypercapnia.KeywordsObstructive Sleep ApneaObstructive Sleep Apnea SyndromeCarotid BodyTotal Peripheral ResistanceSympathetic DenervationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.