[The significance of vasoactive intestinal polypeptide (VIP) in diagnosis of sleep apnea syndrome].

Vasoactive intestinal polypeptide (VIP) is a neurotransmitter of the non-adrenergic and non-cholinergic system (NANC). It has been detected in many organs, including the airways, central and peripheral nervous system, the blood, and CSF. As a result of neuronal overflow, vagal stimulation leads to an elevation of VIP levels in the plasma. VIP leads to the activation of adenyl-cyclase, and thus to elevated cAMP in cells bearing VIP receptors. In 25 patients (24 males, 1 female) with a mean age of 50.3 +/- 9.9 years, and a Broca Index of 134.5 +/- 27.0%, plasma VIP was measured in the morning under conditions of fasting with the aid of an RIA assay (Incstar). Eleven patients (mean age: 49.4 +/- 10.1 years, Broca: 130 +/- 27.0%) had fewer than 100 episodes of apnea during nocturnal sleep (apnea/hypoapnea index 4.4 +/- 4.8). At 6.3 +/- 1.6 pcmoll-1, plasma VIP was markedly lower than that measured in 14 patients (mean age: 51.0 +/- 10.0 years, Broca: 138 +/- 28%) with the sleep apnea syndrome (apnea/hypopnea index 58.5 +/- 24.7 (means = 11.0 +/- 3.0 pcmoll-1, p less than 0.001). A significant correlation was found between the apnea episode occurring every night, and the VIP values (r = 0.64; y = -133 + 40 x VIP) measured in the plasma. The VIP measured in the plasma would appear to be a highly sensitive and highly specific indicator of the appearance of episodes of apnea during nocturnal sleep.