Focaccio A, Volpe M, Ambrosio G, Lembo G, Pannain S, Rubattu S, Enea I, Pignalosa S, Chiariello M
Department of Medicine, Second School of Medicine, University Federico II, Naples, Italy.
Circulation. 1993 Jan;87(1):192-8. doi: 10.1161/01.cir.87.1.192.
Previous studies have shown that infusion of angiotensin II (Ang II) increases plasma concentrations of atrial natriuretic factor (ANF) in vivo. This phenomenon has been considered secondary to the effects of Ang II on cardiac and systemic hemodynamics. The present study was designed to assess whether Ang II may exert a direct stimulatory effect on ANF release from the heart independent of changes in hemodynamics.
Isolated rabbit hearts were perfused in the Langendorff mode. Heart rate, coronary flow, and atrial and left ventricular (LV) volumes were kept constant. After stabilization, Ang II was infused intracoronary at increasing doses (10(-11) to 10(-8) M) in nine hearts and at a single dose of 10(-10) M in 10 hearts. Each infusion lasted for 5 minutes and was followed by a 10-minute washout period. Four hearts received vehicle alone for 80 minutes. Ang II induced a dose-dependent increase in coronary perfusion pressure and in LV developed pressure. ANF release, measured by radioimmunoassay on the extracts of the cardiac effluent, also increased during Ang II infusion and returned to the basal values during the 10-minute washout period. In the control group, coronary perfusion pressure, LV developed pressure, and LV end-diastolic pressure did not change appreciably over the observation period, whereas ANF release progressively decreased during perfusion.
Ang II can directly stimulate cardiac release of ANF in isolated rabbit hearts independently of changes in hemodynamics.
先前的研究表明，体内输注血管紧张素II（Ang II）会增加血浆心钠素（ANF）浓度。这种现象被认为是Ang II对心脏和全身血流动力学影响的继发效应。本研究旨在评估Ang II是否可能独立于血流动力学变化而对心脏ANF释放产生直接刺激作用。
采用Langendorff模式灌注离体兔心。心率、冠脉流量、心房和左心室（LV）容积保持恒定。稳定后，对9颗心脏以递增剂量（10⁻¹¹至10⁻⁸M）冠脉内输注Ang II，对10颗心脏以单一剂量10⁻¹⁰M输注。每次输注持续5分钟，随后有10分钟的洗脱期。4颗心脏仅接受载体80分钟。Ang II导致冠脉灌注压和LV收缩压呈剂量依赖性增加。通过对心脏流出液提取物进行放射免疫测定来测量的ANF释放，在Ang II输注期间也增加，并在10分钟的洗脱期内恢复到基础值。在对照组中，冠脉灌注压、LV收缩压和LV舒张末期压力在观察期内无明显变化，而灌注期间ANF释放逐渐减少。
在离体兔心中，Ang II可独立于血流动力学变化而直接刺激心脏释放ANF。
