Weinstock B S, Bell L, Rutlen D L
Cardiology Section, Yale University School of Medicine, New Haven, Connecticut 06510.
Am J Physiol. 1989 Oct;257(4 Pt 2):H1049-55. doi: 10.1152/ajpheart.1989.257.4.H1049.
Verapamil's influence on intravascular volume (IV) in the total capacitance circulation was examined in anesthetized dogs after mecamylamine or baroreceptor denervation. Blood was drained from the venae cavae to an extracorporeal reservoir and returned to the right atrium at a constant rate so that IV changes could be measured as reciprocal changes in reservoir volume. In 10 dogs, verapamil (50 micrograms/min) caused a decrease in total IV of 74 +/- 12 ml (P less than 0.0005) at 20 min and a decrease in arterial pressure from 79 +/- 5 to 66 +/- 3 mmHg (P less than 0.0005). After evisceration in nine animals, verapamil caused an extrasplanchnic (XSPL) IV decrease of 97 +/- 19 ml (P = 0.08). In 11 animals with separate perfusion and drainage of the splanchnic and XSPL circulations, verapamil caused an XSPL IV decrease of 74 +/- 20 ml (P less than 0.002) and a splanchnic IV increase of 19 +/- 9 ml (P = 0.06). In four animals on cardiopulmonary bypass, IV decreased 154 +/- 66 ml (P less than 0.002) during verapamil administration. Thus total IV decreases due to a decrease in systemic extrasplanchnic volume. Because pressure decreased while arterial flow and venous outflow pressure were constant, a decrease in the resistance to blood return to the central circulation mediates the XSPL volume decrement.
在给予美加明或进行压力感受器去神经支配后，对麻醉犬体内维拉帕米对总容量循环中血管内容量（IV）的影响进行了研究。将腔静脉血液引流至体外储液器，并以恒定速率回输至右心房，以便将IV变化作为储液器容积的反向变化进行测量。在10只犬中，维拉帕米（50微克/分钟）在20分钟时使总IV减少74±12毫升（P<0.0005），动脉压从79±5毫米汞柱降至66±3毫米汞柱（P<0.0005）。在9只动物进行内脏切除后，维拉帕米使内脏外（XSPL）IV减少97±19毫升（P = 0.08）。在11只分别对内脏和XSPL循环进行灌注和引流的动物中，维拉帕米使XSPL IV减少74±20毫升（P<0.002），使内脏IV增加19±9毫升（P = 0.06）。在4只进行体外循环的动物中，维拉帕米给药期间IV减少154±66毫升（P<0.002）。因此，由于全身内脏外容量减少导致总IV减少。由于在动脉血流和静脉流出压力恒定的情况下压力降低，返回中心循环的血流阻力降低介导了XSPL容积的减少。
