Role of peripheral adenosine A(1) receptors in the regulation of sleep apneas in rats.

The effects of administration of N(6)-p-sulfophenyladenosine (p-SPA), a peripheral adenosine A(1) receptor agonist, and 8-(p-sulfophenyl)theophylline (p-SPT), a peripheral adenosine A(1) receptor blocker, on spontaneous apneas were studied in 10 adult Sprague-Dawley rats by monitoring respiration, sleep, and blood pressure for 6 h. Intraperitoneal injection of p-SPA (1 mg/kg) to rats suppressed spontaneous central apneas during non-rapid eye movement sleep by 50% in comparison to control recordings (p = 0.03). This effect was blocked by pretreatment with an equimolar dose of p-SPT (0.67 mg/kg) indicating that p-SPA suppression of apneas was receptor mediated in the peripheral nervous system. Administration of p-SPA did not affect apnea expression in rapid eye movement sleep and had no effect on sleep or blood pressure at the dose tested. Administration of p-SPT (0.67, 6.7, and 30 mg/kg) to rats had no effect on apneas, sleep, or blood pressure. The lack of p-SPT effect on sleep apneas argues against a physiologic role for endogenous adenosine in the peripheral nervous system as a modulator of sleep apnea expression under baseline conditions.