Leenen F H
Hypertension Unit, University of Ottawa Heart Institute, Ontario, Canada.
Blood Press Suppl. 1995;2:35-8.
Both hemodynamic and non-hemodynamic stimuli are recognized as regulators of cardiac growth. The chronic effects of an increase in systolic wall stress on left ventricular (LV) mass in the absence of cardiac sympathetic nerve activity can be assessed in human cardiac transplant recipients. Hypertension develops within several weeks/months after transplantation in patients treated with cyclosporine. Two longitudinal studies have shown that the absolute LV mass remains at control values despite an increase in both blood pressure and body weight. The chronic trophic effects of humoral stimuli on LV mass in the absence of hemodynamic load can be assessed following heterotopic cardiac transplantation into the abdomen of rats, with end to side aorto-aortic anastomosis between the donor and recipient aorta. The transplanted heart functions as a denervated "non-working" Langendorff heart. In these animals, the transplanted heart atrophies by about 30-40% within 5-10 days. Although this atrophy may relate to hemodynamic unloading per se, chronic infusions of methoxamine or isoproterenol can prevent the atrophy. The hemodynamic unloading and/or sympathetic denervation appear to increase the sensitivity for these agonists. The transplanted heart thus offers a unique opportunity to study the interactions of hemodynamic and non-hemodynamic stimuli for cardiac growth.
血流动力学刺激和非血流动力学刺激均被视为心脏生长的调节因素。在无心脏交感神经活动的情况下，收缩期壁应力增加对左心室（LV）质量的慢性影响可在人体心脏移植受者中进行评估。接受环孢素治疗的患者在移植后数周/数月内会出现高血压。两项纵向研究表明，尽管血压和体重均升高，但左心室绝对质量仍维持在对照值。在将心脏异位移植到大鼠腹部且供体和受体主动脉之间进行端侧主动脉 - 主动脉吻合后，可评估在无血流动力学负荷情况下体液刺激对左心室质量的慢性营养作用。移植的心脏起到去神经支配的“非工作”朗格多夫心脏的作用。在这些动物中，移植的心脏在5 - 10天内萎缩约30 - 40%。尽管这种萎缩可能本身与血流动力学卸载有关，但长期输注甲氧明或异丙肾上腺素可防止萎缩。血流动力学卸载和/或交感神经去支配似乎会增加对这些激动剂的敏感性。因此，移植的心脏为研究血流动力学和非血流动力学刺激对心脏生长的相互作用提供了独特的机会。
