title: Relationship between T-wave amplitude and oxygen pulse in guinea pigs in hyperbaric helium and hydrogen.
abstract: Diving is known to induce a change in the amplitude of the T wave (ATw) of electrocardiograms, but it is unknown whether this is linked to a change in cardiovascular performance. We analyzed ATw in guinea pigs at 10-60 atm and 25-36 degreesC, breathing 2% O2 in either helium (heliox; n = 10) or hydrogen (hydrox; n = 9) for 1 h at each pressure. Core temperature and electrocardiograms were detected by using implanted radiotelemeters. O2 consumption rate was measured by using gas chromatography. In a previous study (S. R. Kayar and E. C. Parker. J. Appl. Physiol. 82: 988-997, 1997), we analyzed the O2 pulse, i.e., the O2 consumption rate per heart beat, in the same animals. By multivariate regression analysis, we identified variables that were significant to O2 pulse: body surface area, chamber temperature, core temperature, and pressure. In this study, inclusion of ATw made a significantly better model with fewer variables. After normalizing for chamber temperature and pressure, the O2 pulse increased with increasing ATw in heliox (P = 0.001) but with decreasing ATw in hydrox (P < 0.001). Thus ATw is associated with the differences in O2 pulse for animals breathing heliox vs. hydrox.
authors.affiliation: Albert R. Behnke Diving Medicine Research Center, Naval Medical Research Institute, Bethesda, Maryland 20889-5607, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Kayar
authors.forename: E C
authors.initials: EC
authors.lastname: Parker
authors.forename: E O
authors.initials: EO
authors.lastname: Aukhert
mesh_terms: D000399:Air Pressure; D000818:Animals; D004242:Diving / Q000502:physiology; D004562:Electrocardiography; D006168:Guinea Pigs; D006339:Heart Rate / Q000502:physiology; D006371:Helium / Q000008:administration & dosage / Q000494:pharmacology*; D006610:High Pressure Neurological Syndrome / Q000503:physiopathology; D006859:Hydrogen / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008954:Models, Biological; D010101:Oxygen Consumption / Q000502:physiology*; D012044:Regression Analysis; D013686:Telemetry
chemical_list: D006371:Helium; D006859:Hydrogen