Cell swelling, impulse conduction, and cardiac arrhythmias in the failing heart. Opposite effects of angiotensin II and angiotensin (1-7) on cell volume regulation.
The influence of hypotonic solution on cell volume and electrophysiology properties of the failing heart of cardiomyopathic hamsters (TO-2) was investigated. The results showed an increase in cell volume of quiescent isolated ventricular myocytes by 66% within 30 min. Angiotensin (1-7) [Ang (1-7)] (10(-8) M) administered to isotonic solution, elicited a gradual decline in cell volume and a significant decrease of the swelling-activated chloride current (I (Clswell)). The effect of Ang (1-7) on cell volume was inhibited by ouabain (10(-7) M). Angiotensin II (10(-8) M) caused cell swelling and increased I (Clswell). Experiments performed on isolated left ventricles of cardiomyopathic hamsters at an advanced stage of the disease, indicated that hypotonic solution prepared by diluting the normal Krebs solution by 25%, showed a gradual decrease of conduction velocity, generation of early after depolarizations and block of impulse conduction within 10 min. Implications to myocardial ischemia are discussed.
De Mello
Walmor C
WC
Department of Pharmacology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR, 00936-5067, USA. walmor.de-mello@upr.edu
D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001145:Arrhythmias, Cardiac; D009202:Cardiomyopathies; D048429:Cell Size / Q000187:drug effects*; D002478:Cells, Cultured; D006224:Cricetinae; D004594:Electrophysiology; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology*; D006333:Heart Failure / Q000473:pathology* / Q000503:physiopathology*; D006352:Heart Ventricles / Q000473:pathology; D007038:Hypotonic Solutions / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials; D032383:Myocytes, Cardiac / Q000473:pathology; D010446:Peptide Fragments / Q000494:pharmacology*; D011674:Pulse
D007038:Hypotonic Solutions; D010446:Peptide Fragments; D000804:Angiotensin II; D000803:Angiotensin I; C118790:angiotensin I (1-7)