Received February 9, 2006
Revised April 6, 2006
Accepted after revision June 12, 2006
Coronary reactive hyperaemia and arterial pressure in anaesthetized goats
Nuria Fernández 1,
Luis Monge 1,
Angel Luis García-Villalón 1,
Godofredo Diéguez 1*
1 Facultad Medicina, Universidad Autónoma
* To whom correspondence should be addressed. E-mail: gdieguez{at}uam.es.
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Abstract |
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To study the effects of arterial pressure on coronary reactive hyperaemia, left circumflex coronary artery flow was measured, and reactive hyperaemia was determined after 5, 10 or 20 s of occlusion of this artery in anaesthetized goats during normotension, hypertension and hypotension. During hypertension induced by aortic constriction (mean arterial pressure, MAP = 140 ± 6 mmHg) coronary vascular resistance (CVR), reactive hyperaemia (ratio of peak hyperaemic flow to control flow and ratio of repayment to debt) and the decrease in coronary vascular resistance (CVR) during the peak in hyperaemic flow were comparable to those during normotension. During hypertension induced by noradrenaline (MAP = 144 ± 6 mmHg) CVR was 16% lower (P < 0.05), reactive hyperaemia was reduced by 14_25% (P < 0.05) and the decrease in CVR during the peak in hyperaemic flow was lower than the values of these parameters during normotension. During hypotension induced by constriction of the caudal vena cava (MAP = 40 ± 4 mmHg) CVR was 22% lower (P < 0.05), reactive hyperaemia was reduced by 25_65 % lower (P<0.05) and the decrease in CVR during the peak in hyperaemic flow was lower compared to the values of these parameters during normotension. During hypotension induced by isoproterenol (MAP = 45 ± 4 mmHg) CVR was 59% lower, reactive hyperaemia was reduced by 55_100% (P < 0.01) and the decrease in CVR during the peak in hyperaemic flow was lower compared to the values of these parameters during normotension. Arterial pressure is a main determinant of coronary reactive hyperaemia after brief periods of ischaemia, and the relationship between arterial pressure and reactive hyperaemia may depend in part on changes in CVR after variations in arterial pressure. These changes in CVR may be related to the action on coronary vessels of myocardial factors and vascular myogenic mechanisms.
Key Words:
Coronary blood flow, Hypertension, Hypotension
