The haemodynamic effects of endurance training with or without anabolic steroid treatment (nandrolone decanoate, 5.0 mg kg-1 week-1) were studied before and after a six-week sedentary period in anaesthetized, open-chest rats during isoproterenol and CaCl2 loads. In comparison to the control group (CG I, n = 13) endurance training (TG I, n = 10) increased the resting stroke index significantly, end-diastolic pressure and during CaCl2 infusion the end-diastolic and end-systolic volumes. Peripheral resistance decreased in TG I during both inotropic loads but increased in CG I (P less than 0.01 between the groups). After combined endurance training and anabolic steroid treatment (TSG I, n = 16) the haemodynamic state was similar to that in CG I except peripheral resistance which was even higher than in CG I. The heart weight to body weight ratio was significantly greater both in TG I and TSG I than in CG I. After a six-week deconditioning period the haemodynamic values were essentially similar in endurance trained (TG II, n = 10) and in control rats (CG II, n = 12). After the sedentary period, in the simultaneously trained and anabolic steroid-treated group (TSG II, n = 13) stroke index and end-diastolic volume decreased more during isoproterenol load when compared with TG II or CG II (P less than 0.05 between the groups). Peripheral resistance was higher in the TSG II than in the two other groups. In conclusion, the enhanced pumping performance of the heart by increased left ventricular diastolic filling after endurance training is attenuated by simultaneous anabolic steroid treatment which further increases the peripheral resistance. Detraining reversed the main training effects in six weeks and simultaneous anabolic steroid treatment led to a decreased left ventricular filling and to elevated peripheral resistance after the sedentary period.

The haemodynamic effects of endurance training and physical deconditioning were studied in anaesthetized rats using aortic and left ventricular pressure recordings and volume measurements by thermodilution method during isoproterenol and CaCl2 loads. The resting stroke volume was significantly larger in the training group (TG I, n = 10) than in the control group (CG I, n = 13). During the CaCl2 infusion stroke index, end-diastolic and end-systolic volumes increased in the TG I, but decreased in the CG I. Both isoproterenol and CaCl2 decreased systemic vascular resistance in the TG I, but increased it in the CG I. After a six-week deconditioning following training period (TG II, n = 10) stroke index, end-diastolic and end-systolic volumes decreased during CaCl2 and isoproterenol infusions similarly to the control deconditioning group (CG II, n = 12). These responses differed significantly from those observed in the TG I. Peripheral resistance increased in both the CG II and the TG II. Cardiac hypertrophy observed during training was partly reversed after the deconditioning period. In conclusion, endurance training improves the pumping performance of the rat heart by enhancing the diastolic filling of the left ventricle and decreasing peripheral resistance during inotropic load. Left ventricular contractility is not affected. A six-week deconditioning period after endurance training returns the haemodynamic changes to sedentary levels.

The hemodynamic and metabolic effects of acetate were studied in rats in vivo and in the isolated perfused heart. Hemodynamic parameters, myocardial phosphagens, inorganic phosphate, and adenosine were measured in vivo. Acetate uptake, coronary flow, O2 consumption, parameters of the cellular energy state, and hypoxanthine compounds and their washout were measured in heart perfusion experiments. Heart rate (HR), cardiac output, and the peak derivative of the left ventricular pressure rise (dP/dtmax) increased significantly during acetate infusion in vivo, but mean arterial pressure, systolic arterial pressure, and systemic vascular resistance decreased. Heart muscle ATP concentrations decreased after 7 min of acetate infusion. In vivo cardiac work load (HR.(peak left ventricular pressure] showed a positive correlation with tissue adenosine concentration and a negative correlation with phosphorylation potential. Acetate uptake in the perfused hearts was about 2.5 mumol/min per gram wet weight. Acetate perfusion increased O2 consumption and coronary flow concomitantly with a decrease in tissue ATP concentration. Tissue AMP and perfusate effluent adenosine concentration and adenosine output increased significantly, perfusate adenosine showing a non-linear positive correlation with coronary flow. The results demonstrate that acetate induces considerable changes in hemodynamics and metabolism in the heart.

The haemodynamic effects in the early phase of canine acute experimental pancreatitis (AP) were studied using a cardiac catheterization technique. AP was induced in anaesthetized dogs with an infusion of trypsin-sodium-taurocholate into the pancreatic duct. The initial haemodynamic measurements were performed after the preparation of the animal and 5 min after the induction of AP. Thereafter, pressure and volume parameters were measured at 10 min intervals. AP induced significant increases in heart rate, dP/dtmax and mean arterial pressure, but a decrease in Vmax 5 min after the induction of AP. After the initial phase, the heart rate remained significantly increased, while constant and significant decreases of stroke volume, cardiac output, end-diastolic volume and end-diastolic pressure developed. The parameters of the contractility of the left ventricle were not affected to the same extent. It is suggested that the circulatory failure observed in AP, characterised by a prompt reduction of cardiac output, was primarily due to a heavy reduction in preload. This supports the theory that cardiac output is primarily affected by impaired venous return with consequently decreased preload rather than by a loss of ventricular contractility. Hence, the existence of a myocardial depressant factor in the early phase of experimental AP does not gain support from the present results.

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