Naslov
Central chemoreflex sensitivity and sympathetic neural outflow in elite breath hold divers

Autori
Dujić, Željko ; Ivančev, Vladimir ; Heusser, Karsten ; Džamonja, Gordan ; Palada, Ivan ; Valić, Zoran ; Tank, Jens ; Obad, Ante ; Baković, Darija ; Diedrich, Andre ; Joyner, Michael, J. ; Jordan, Jens

Izvornik
Journal of Applied Physiology (0021-8987) 104 (2008), 1; 205-211

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
ultrasound; MSNA; apnea; human

Sažetak
Repeated hypoxemia in obstructive sleep apnea patients increases sympathetic activity thereby promoting arterial hypertension. Elite breath-holding divers are exposed to similar apneic episodes and hypoxemia. We hypothesized that trained divers would have increased resting sympathetic activity and blood pressure, as well as an excessive sympathetic nervous system response to hypercapnia. We recruited eleven experienced divers and nine control subjects. During the diving season preceding the study, divers participated in 7.3± ; 1.2 diving fish-catching competitions and 76.4± ; 14.6 apnea training sessions with the last apnea 3-5 days before testing. We monitored beat-by-beat blood pressure, heart rate, femoral artery blood flow, respiration, end tidal CO2, and muscle sympathetic nerve activity (MSNA). After a baseline period, subjects began to rebreath a hyperoxic gas mixture to raise end-tidal CO2 to 60 mm Hg. Baseline MSNA frequency was 31± ; 11 bursts/min in divers and 33± ; 13 bursts/min in control subjects. Total MSNA activity was 1.8± ; 1.5 au/min in divers and 1.8± ; 1.3 au/min in control subjects. Arterial oxygen saturation did not change during rebreathing while end-tidal CO2 increased continuously. The slope of the hypercapnic ventilatory and MSNA response was similar in both groups. We conclude that repeated bouts of hypoxemia in elite, healthy breath-holding divers do not lead to sustained sympathetic activation or arterial hypertension. Repeated episodes of hypoxemia may not be sufficient to drive an increase in resting sympathetic activity in the absence of additional comorbidities.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

POVEZANOST RADA