Hypoxic pressor response, cardiac size, and natriuretic peptides are modified by long-term intermittent hypoxia.
We investigated whether the effect of long-term intermittent hypoxia (LTIH) on cardiovascular function may be modified by preexisting genetic traits. To induce LTIH experimentally, cycles of 90-s hypoxia (nadir 6%) followed by 90-s normoxia were applied to six Wistar-Kyoto and six spontaneously hypertensive rats during 8 h daily. Comparison with the same number of control animals after 70 days revealed no alteration of intra-arterial blood pressure or heart rate. Blood pressure responsiveness to a brief hypoxic stimulus was enhanced in the LTIH animals, regardless of strain, whereas the hypoxia-induced increase in heart rate was abolished. In the spontaneously hypertensive but not the Wistar-Kyoto rats, LTIH increased left ventricular weight-to-body weight ratio and content of atrial natriuretic peptide mRNA. Expression of B-type natriuretic peptide was unchanged (Northern blot). Slightly increased right ventricular weight-to-body weight ratios in the LTIH animals were associated with higher right ventricular atrial natriuretic peptide and B-type natriuretic peptide mRNA amounts. Consequently, the effects of LTIH on different components of cardiovascular function appear incompletely related to each other and differentially influenced by constitutional traits.
Kraiczi
H
H
Department of Clinical Pharmacology, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
Magga
J
J
Sun
X Y
XY
Ruskoaho
H
H
Zhao
X
X
Hedner
J
J
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism*; D001794:Blood Pressure; D002908:Chronic Disease; D006352:Heart Ventricles; D006439:Hemodynamics; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D020097:Natriuretic Peptide, Brain; D009929:Organ Size; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D012333:RNA, Messenger; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor