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 compara...

introduction: ouabaine is a well-known atrioventricular (av) node depressant agent, but its effects on functional properties of the av node have not been cleared. the aim of the present study was to determine how ouabaine administration modifies the rate-dependent properties of the av node. methods: selective stimulation protocols were used to quantify independently electrophysiological propert...

Abstract Introduction: Isolated perfused heart models such as perfusion and superfusion are commonly used for mammalian heart research. However, there are several fundamental limitations in the current techniques. In perfusion model, a suitable cannula is connected to the aorta and the perfusion is retrogradely performed. But, electrode displacement is a potential unwanted event resulted fr...

objective(s) in the present study, the effects of aqueous-ethanolic extract from rosa damascena on heart rate and contractility were examined. materials and methods isolated guinea-pig hearts were perfused through aorta in a langendorff mode. heart rate (hr) and contractility were determined in the presence of four concentrations of the extract (0.1, 0.2, 0.4 and 1.0 mg %) and isoprenaline (1, ...

     Carnitine is a vital biologic substance for transporting fatty acids into myocytes. It also facilitates fatty acids β-oxidation for energy production. In this study, effects of L-carnitine (L-Car) on apoptosis in the ischemic isolated rat heart were investigated. Male Sprague-Dawley rats were divided into four groups and anesthetized by sodium pentobarbital. The heart was removed and mount...

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...

We tested the hypothesis that while absolute extrasystolic (ES) and postextrasystolic (PES) dP/dtmax would be influenced by pacing site, if these values were normalized by the steady-state dP/dtmax obtained with the same pacing site, they would be independent of pacing site. We employed an isovolumetrically contracting isolated heart preparation with a balloon placed in the left ventricle. Paci...

Normal heart function requires generation of a regular rhythm by sinoatrial pacemaker cells and the alteration of this spontaneous heart rate by the autonomic input to match physiological demand. However, the molecular mechanisms that ensure consistent periodicity of cardiac contractions and fine tuning of this process by autonomic system are not completely understood. Here we examined the cont...

We studied the effect of ejection on end-systolic pressure in isolated heart preparations. Ejecting beats were compared with isovolumic beats having the same volume as at end systole. While holding end-systolic volume constant, various stroke volumes, including negative stroke volumes (volume injected during systole), were imposed using a predetermined volume command. After switching contractio...

Introduction: Beat-to-beat variation in heart rate shows a complex dynamics, and this complexity is changed during systemic inflammatory response syndrome (e.g. sepsis). It is not known whether or not cardiac pacemaker dynamical rhythm is affected by sepsis. The aim of this study was to investigate heart rate dynamics of isolated heart as well as expression of pacemaker channels (HCN) in a r...