Bin Jian-Ping, Le D Elizabeth, Jayaweera Ananda R, Coggins Matthew P, Wei Kevin, Kaul Sanjiv
Cardiovascular Imaging Center, the Cardiovascular Division, University of Virginia, Charlottesville 22908, USA.
J Am Soc Echocardiogr. 2003 Aug;16(8):871-9. doi: 10.1067/S0894-7317(03)00423-1.
The direct effects of dobutamine on capillary blood volume (VOL) and blood flow velocity (VEL) are not known. We hypothesized that these would be more similar to that of adenosine because of its effects on the beta(2) receptors on the coronary circulation. A total of 9 open-chest anesthetized dogs were studied after placement of 2 noncritical stenoses at rest and during separate intracoronary administrations of 5 microg/kg(-1)/min(-1) of adenosine and 2 microg/kg(-1)/min(-1) of dobutamine. VOL and VEL were measured using myocardial contrast echocardiography, wall thickening with 2-dimensional echocardiography, and myocardial blood flow (MBF) with radiolabeled microspheres. Dobutamine increased the rate-pressure product significantly, whereas adenosine had no effect on the rate-pressure product. In the normal myocardium, adenosine had no effect on VOL and increases in MBF were all a result of increases in VEL. Dobutamine also caused mostly an increase in VEL and only a 30% increase in VOL indicating modest capillary recruitment. In the bed with stenosis both drugs attenuated increase in MBF by the same amount, which was associated with an attenuation in the increase in VEL secondary to a 15% increase in capillary resistance because of capillary derecruitment. The MBF-wall thickening relation was described for both drugs by the same function: y = 1 - exp(x) with wall thickening being significantly higher for dobutamine compared with adenosine for each level of MBF. We conclude that the increase in MBF in the normal myocardium with intracoronary dobutamine occurs mostly from an increase in VEL rather than from an increase in VOL. In the bed with a noncritical stenosis, the increases in MBF and VEL are similar for both drugs. Similar to intracoronary adenosine, intracoronary dobutamine also caused capillary derecruitment distal to a noncritical coronary stenosis.
多巴酚丁胺对毛细血管血容量（VOL）和血流速度（VEL）的直接影响尚不清楚。我们推测，由于其对冠状动脉循环中β₂受体的作用，这些影响可能与腺苷更为相似。对9只开胸麻醉犬进行了研究，在静息状态下以及分别冠状动脉内给予5μg/kg⁻¹/min⁻¹腺苷和2μg/kg⁻¹/min⁻¹多巴酚丁胺期间，放置了2处非临界狭窄。使用心肌对比超声心动图测量VOL和VEL，使用二维超声心动图测量室壁增厚，使用放射性微球测量心肌血流量（MBF）。多巴酚丁胺显著增加心率-血压乘积，而腺苷对心率-血压乘积无影响。在正常心肌中，腺苷对VOL无影响，MBF的增加完全是VEL增加的结果。多巴酚丁胺也主要导致VEL增加，VOL仅增加30%，表明毛细血管募集适度。在有狭窄的心肌床中，两种药物均使MBF的增加量减少相同程度，这与由于毛细血管去募集导致毛细血管阻力增加15%继发的VEL增加量减少有关。两种药物的MBF-室壁增厚关系由相同函数描述：y = 1 - exp(x)，对于每个MBF水平，多巴酚丁胺的室壁增厚显著高于腺苷。我们得出结论，冠状动脉内给予多巴酚丁胺时，正常心肌中MBF的增加主要源于VEL的增加而非VOL的增加。在有非临界狭窄的心肌床中，两种药物的MBF和VEL增加相似。与冠状动脉内给予腺苷类似，冠状动脉内给予多巴酚丁胺也会导致非临界冠状动脉狭窄远端的毛细血管去募集。
