Hypercholesterolemia blunts forearm vasorelaxation and enhances the pressor response during acute systemic hypoxia.
OBJECTIVE
During hypoxia, active substances released by the endothelium play a key role in the cardiovascular and respiratory responses elicited to optimize oxygen delivery. As hypercholesterolemia is a major cause of endothelial dysfunction, it may interfere with these responses.


RESULTS
We studied cardiovascular and ventilatory responses to acute systemic hypoxia in 14 patients with hypercholesterolemia (HC) and 13 control (CO) subjects. Oxygen saturation decreased similarly in both groups. Diastolic blood pressure increased only in the HC group (P=0.0002) and, despite systolic blood pressure increases both in the HC group, 140+/-4 (95% confidence interval [CI],131 to 149 mm Hg) to 154+/-4 mm Hg (95% CI,145 to 164 mm Hg), and in the CO group, 133+/-3 (95% CI,126 to 140 mm Hg) to 140+/-4 mm Hg (95% CI,132 to 148 mm Hg), the HC group showed an enhanced pressor response (P=0.03, group comparison). Both groups had increased forearm blood flow, but the decrease in forearm vascular resistance in the CO group, 40+/-5 (95% CI, 30 to 51 UR) to 31+/-4 UR (95% CI,23 to 39 UR) (P=0.0001) was not seen in the HC group, 29+/-3 (95% CI, 22 to 37 UR) to 26+/-3 UR (95% CI, 20 to 33 UR), (P=0.03, group comparison).


CONCLUSIONS
Hypercholesterolemic patients demonstrate a hyperreactive pressor response and absence of forearm vasodilation during acute systemic hypoxia.
Barreto-Filho
José Augusto S
JA
The Hypertension Unit, Heart Institute (InCor), University of São Paulo Medical School, Brazil. jose.barreto@incor.usp.br
Consolim-Colombo
Fernanda Marciano
FM
Guerra-Riccio
Grazia Maria
GM
Santos
Raul D
RD
Chacra
Ana Paula
AP
Lopes
Heno Ferreira
HF
Teixeira
Sandra H
SH
Martinez
Tânia
T
Krieger
José Eduardo
JE
Krieger
Eduardo Moacyr
EM
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood / Q000378:metabolism; D005260:Female; D005542:Forearm / Q000098:blood supply* / Q000503:physiopathology; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011311:Pressoreceptors / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D002245:Carbon Dioxide