Increased sodium-proton antiporter activity in patients with obstructive sleep apnoea.
Cytosolic pH (pH(i)) and the activity of the sodium-proton antiporter (Na(+)/H(+) antiporter) were measured in lymphocytes from 22 patients with obstructive sleep apnoea and from 24 age-matched healthy subjects (Controls). The cellular Na(+)/H(+) antiporter was measured spectrophotometrically using a pH-sensitive fluorescent dye after intracellular acidification using sodium propionate. Resting pHi was similar in lymphocytes from patients with obstructive sleep apnoea and from controls (7.36 +/- 0.20, n=22; vs. 7.35 +/- 0.19, n=24; mean +/- SD). The Na(+)/H(+) antiporter activity was significantly higher in patients with obstructive sleep apnoea than in controls (11.87 +/- 3.26 x 10(-3) pH(i)/s vs. 4.38 +/- 1.40 x 10(-3) pH(i)/s; P < 0. 0001). The apparent affinity of the Na+/H+ antiporter was not significantly different between the groups (6.90 +/- 0.23 vs. 6.87 +/- 0.20). In patients with obstructive sleep apnoea the activity of the Na(+)/H(+) antiporter remained stable during the night. The activity of the Na(+)/H(+) antiporter was 13.49 +/- 4.80 x 10(-3) pH(i)/s at 20.00 and 13.26 +/- 6.13 x 10(-3) pH(i)/s at 02.00. From the present results it is concluded that an increased cellular Na(+)/H(+) antiporter activity may be a genetic marker for patients who are predisposed to obstructive sleep apnoea.
Tepel
M
M
Medizinische Klinik I, Universitätsklinik Marienhospital, Ruhr-Universität Bochum, Germany. Martin.Tepel@ruhr-uni-bochum.de
Sanner
B M
BM
van der Giet
M
M
Zidek
W
W
D000368:Aged; D017920:Antiporters / Q000097:blood*; D003600:Cytosol / Q000378:metabolism; D004576:Electromyography; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011522:Protons; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000097:blood*; D012965:Sodium Chloride / Q000097:blood*
D017920:Antiporters; D005456:Fluorescent Dyes; D011522:Protons; D012965:Sodium Chloride