HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Topcuolu, M S. Articles by Ulus, T. Search for Related Content PubMed Articles by Topcuolu, M S. Articles by Ulus, T.

Electromechanical Effects of Protamine and Verapamil in Rat Papillary Muscle

M ah Topcuolu, MD, Mustafa Itein, PhD^1,, Gülay Loolu, MD^2,, smail Günay, PhD^1,, Acar Tokcan, MD, Tümer Ulus, MD

Department of Thoracic and Cardiovascular Surgery 1 Department of Biophysics 2 Department of Physiology Çukurova University Medical Faculty Adana, Turkey

For reprint information contact: M ah Topcuolu, MD Tel: 90 322 338 6627 Fax: 90 322 338 6572 email: sahtopcu{at}pamuk.cc.cu.edu.tr Department of Thoracic and Cardiovascular Surgery, Çukurova University Medical Faculty, Balcali, Adana 01330, Turkey.

The electromechanical effects of protamine sulfate and the calcium channel blocker verapamil on rat cardiac and skeletal muscles were studied using isolated left ventricular papillary muscle and phrenic nerve-hemidiaphragm preparations. Protamine produced significant decreases in isometric force in the cardiac tissue and contracture developed at concentrations of 40 and 80 mg•L^–1. Isometric force also decreased significantly with verapamil at concentrations of 0.757 and 7.57 mg•L^–1. Both drugs caused significant decreases in the contractile force of hemidiaphragm muscle when the tissue was stimulated indirectly. Protamine and verapamil caused the resting membrane potential and the amplitude of the action potential to decrease in cardiac tissue and overshoot failed to develop with 80 mg•L^–1 of protamine or 7.57 mg•L^–1 of verapamil. These bioelectrical changes developed in a dose-dependent manner. It was concluded that protamine had a similar effect to that of calcium channel blockers and it may act through a reduction of cellular calcium. This effect on cardiac tissue may be mediated through the sarcolemmal ion pumps or channels, leading to changes in calcium homeostasis.