Reoxygenated effluent of Tyrode-perfused heart affects papillary muscle contraction independent of cardiac perfusion.
نویسندگان
چکیده
OBJECTIVE We determined, via a bioassay, if inotropic factors are released in the coronary circulation of the rat heart and if changes in cardiac perfusion change papillary muscle inotropy. METHODS An isolated isometrically contracting rat papillary muscle (n = 5, acceptor) was superfused with Tyrode or with reoxygenated coronary venous effluent from an isolated isovolumically beating rat heart (donor) at 27 degrees C, which was perfused with Tyrode according to Langendorff. The superfusion solution in the muscle bath was exchanged completely in 90 s. During coronary venous effluent superfusion, the flow of the heart (donor) was changed in steps. RESULTS The peak force of the papillary muscle (acceptor) was unaffected by a change from Tyrode to coronary venous effluent superfusion, but time to half relaxation (RT 1/2) significantly increased by 23.0 +/- 9.0% (mean +/- s.d.) and positive dF/dtmax significantly decreased by 14.6 +/- 4.7%. These twitch characteristics were unaffected by changes in coronary perfusion while in the heart isovolumic developed left ventricular pressure did increase with perfusion (the Gregg phenomenon). CONCLUSIONS Factors that affected papillary muscle contractility are released into the coronary circulation, but their effect is independent of the magnitude of coronary perfusion.
منابع مشابه
Decrease in coronary vascular volume in systole augments cardiac contraction.
Coronary arterial inflow is impeded and venous outflow is increased as a result of the decrease in coronary vascular volume due to cardiac contraction. We evaluated whether cardiac contraction is influenced by interfering with the changes of the coronary vascular volume over the heart cycle. Length-tension relationships were determined in Tyrode-perfused rat papillary muscle and when coronary v...
متن کاملEndothelial cells regulate cardiac contractility.
Endothelial cells lining the lumen of blood vessels contain the receptors for many substances that alter the contractile tone of smooth muscle in the walls of the blood vessels. In response to their interaction with the signal substances, the endothelial cells release vasoactive factors that modify the contractile state of the vascular smooth muscle. This study was conducted to determine if end...
متن کاملDoes Heart Affect Peripheral Vascular Resistance Following Myocardial Ischemia and Reperfusion?
Objective(s) The aim of this study was to investigate the overall effect of cardiac vasoactive factors during coronary occlusion and reperfusion on peripheral vascular tone, using a sequential isolated rabbit heart-ear perfusion model. Materials and Methods Isolated ears were perfused with the effluent of isolated hearts subjected to ischemia (30 min) and reperfusion (180 min, n=6). The comp...
متن کاملCardiac endothelial cells modulate contractility of rat heart in response to oxygen tension and coronary flow.
The aim of this study was to determine if endothelial cells in the heart release substances into the coronary perfusion medium that modify the contractility of myocardial cells. To assay the effects on the contractility of cardiac muscle of fluid that has passed through the coronary vasculature, a new method has been developed based on the cascade principle used to study vascular smooth muscle ...
متن کاملAcute and specific collagen type I degradation increases diastolic and developed tension in perfused rat papillary muscle.
Collagen degradation is suggested to be responsible for long-term contractile dysfunction in different cardiomyopathies, but the effects of acute and specific collagen type I removal (main type in the heart muscle) on tension have not been studied. We determined the diastolic and developed tension length relations in isometric contracting perfused rat papillary muscles (perfusion pressure 60 cm...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Cardiovascular research
دوره 33 1 شماره
صفحات -
تاریخ انتشار 1997