Abstract:
INTRODUCTION:Heart rate affects coronary flow, but the mechanism is complex. The relationship between rhythm and flow is unclear, especially in experimental settings used for determining drug actions. The present study examined whether ventricular irregularity influences coronary flow independently of heart rate. METHODS:Guinea pig hearts were perfused (Langendorff mode) at constant pressure. Hypokalemic Krebs solution facilitated spontaneous development of arrhythmias. The ECG, left ventricular and perfusion pressures were recorded, and the coronary flow was measured. Beat-to-beat ventricular cycle length variability was quantified. Hearts were retrospectively allocated to arbitrary 'Low' or 'High' RR variability groups. RESULTS:A positive linear correlation was found between mean ventricular rate and coronary flow. The slope of the regression line was significantly greater in the 'High' versus 'Low' RR variability group, with greater coronary flow values in the 'High' RR variability group in the physiological heart rate range. During regular rhythm, left ventricular pressure exceeded perfusion pressure and prevented coronary perfusion at peak systole. However, ventricular irregularity significantly increased the number of beats in which left ventricular pressure remained below perfusion pressure, facilitating coronary perfusion. DISCUSSION:In isolated hearts, cycle length irregularity increases the slope of the positive linear correlation between mean ventricular rate and coronary flow via producing beats in which left ventricular pressure remains below perfusion pressure. This means that changes in rhythm have the capacity to influence coronary flow independently of heart rate in isolated hearts perfused at constant pressure, which should be noted in drug studies on arrhythmias performed in Langendorff hearts.
journal_name
J Pharmacol Toxicol Methodsjournal_title
Journal of pharmacological and toxicological methodsauthors
Takács H,Kui P,Farkas AS,Sarusi A,Forster T,Papp JG,Varró A,Curtis MJ,Shattock MJ,Farkas Adoi
10.1016/j.vascn.2015.10.001subject
Has Abstractpub_date
2016-01-01 00:00:00pages
45-52eissn
1056-8719issn
1873-488Xpii
S1056-8719(15)00273-7journal_volume
77pub_type
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journal_title:Journal of pharmacological and toxicological methods
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