Changes in the aortic wall oxygen tensions of hypertensive rabbits. Hypertension and aortic wall oxygen

Hypertension is a known risk factor for atherosclerosis. We hypothesize that hypertension causes artery wall hypoxia that contributes to the formation of atherosclerotic lesions. Therefore, we examined the effect of hypertension on the transarterial wall oxygen gradient of the rabbit aorta. Hypertensive rabbits were created by unilateral nephrectomy and contralateral renal artery narrowing. Transarterial wall oxygen gradients of the infrarenal aorta were measured using an oxygen microelectrode 14-16 weeks (short-term hypertension) and 56-58 weeks (long-term hypertension) after the rabbits were made hypertensive. The transarterial wall oxygen gradients showed significant differences among the groups. Short-term hypertension caused significantly higher oxygen tensions in the outer 30% of the artery wall and significant thinning of the artery wall when compared with long-term hypertension and control groups. Long-term hypertension caused significantly lower oxygen tensions in the inner 40% of the artery wall and significant thickening of the artery wall when compared with short-term hypertension and control groups. These changes were noted despite no difference in the partial pressure of oxygen in arterial blood or visual evidence of atherosclerotic lesion formation in the three groups. These findings suggest that hypertension alters the transarterial wall oxygen gradient. This altered transarterial wall oxygen gradient may contribute to the formation of atherosclerotic lesions.