Effect of dopamine on local segment work and O2 consumption in collateral-dependent myocardium
Kedem, J.; Wright, C.; Scholz, P.M.; Weiss, H.R.
American Journal of Physiology 267(1 Pt 2): H17-H23
1994
ISSN/ISBN: 0002-9513 PMID: 8048582 Document Number: 427142
To test the hypothesis that dopamine-stimulated work and myocardial O-2 consumption (M ovrhdot VO-2) in collateral-dependent myocardium would be reduced, Ameroid constrictors were implanted around the circumflex coronary artery (CFX) in nine dogs. Four weeks later, in an anesthetized open-chest preparation, segment length (ultrasonic dimension gauge) and force (miniature force transducer) were measured in myocardium supplied by the CFX and left anterior descending (LAD) coronary arteries. Work in each region was calculated as the systolic area under the force-length curve. Corresponding regional M ovrhdot VO-2 was calculated from local O-2 extraction (microspectrophotometry) and flow (radiolabeled microspheres). Dopamine infusion (15 mu-g cntdot kg-1 cntdot min-1)increased regional work from 262 +- 56 to 733 +- 171 mm cntdot g cntdot min-1 in the control (LAD) region, but to a much smaller extent in the collateral-dependent (CFX) region (from 249 +- 82 to 414 +- 81 mm cntdot g cntdot min-1). However, regional M ovrhdot VO-2 increased to about the same extent in the CFX (from 6.0 +- 0.7 to 12.4 +- 0.9 ml O-2 cntdot min-1 cntdot 100 g- 1) and the LAD region (from 7.0 +- 0.6 to 14.5 +- 1.3 ml O-2 cntdot min-1 cntdot 100 g-1). O-2 extraction was not elevated in the CFX region. Therefore, the functional impairment was not secondary to O-2 supply or consumption limitations.