Alcohol, Vol. 10, pp. 285-290, 1993 0741-8329/93 $6.00 + .00 Printed in the U.S.A. All rightsreserved. Copyright ©1993PergamonPress Ltd. Cocaethylene Toxicity in Rat Primary Myocardial Cell Cultures ALLISON A. WELDER, l LISA J. DICKSON AND RUSSELL B. MELCHERT College of Pharmacy, Division of Medicinal Chemistry and Pharmacodynamics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190 Received 19 October 1992; Accepted 18 January 1993 WELDER, A. A., L. J. DICKSON AND R. B. MELCHERT. Cocaethylene toxicityin ratprimary myocardialcellcul. tures. ALCOHOL 10(4) 285-290, 1993.-Cocaethylene is a unique cocaine metahulite formed in the presence of ethanol by the liver. Neither acute nor chronic cardiotoxic effects of this metaholite have been investigated. The purpose of this study was to establish a time- and dose-dependent toxicity profile for cocaethyleue in primary myocardial cell cultures established from 3-5-day-old Sprague-Dawley rats. Alterations in lactate dehydrngeuase (LDH) release, lysosomal neutral red (NR) retention, thiobarbituric acid-reactive substances (TBARS), morphology, and beating activity were evaluated after treatment of cultures with cocaethylene doses ranging from 1.0 × 10-3 to 1.0 × 10 -9 M from I to 24 h. LDH release was significantly elevated after 24 h only with those cultures exposed to the highest dose of cocaethylene (1.0 × 10-j M). The highest dose of cocaethylene also significantly depressed NR retention. While all doses of cocaethylene depressed contractile activity and altered cellular morphology by 24 h, there were no TBARS formed up to 15 h. Thus, both low and high doses of cocaethyleue are injurious to the cellular integrity and contractility of myocardial cell cultures. Future studies are warranted to determine mechanisms of cocaethylene toxicity in this in vitro model of spontaneously contracting myocardial cells. Cocaethylene Cardiotoxicity Lactate dehydrogeuase Neutral red Beating rates Thioharbituric acid-reactive substances Myocardial cell cultures In vitro Morphology ALTHOUGH it was reported over a decade ago that cocaine metaholites were found in humans who also ingested ethanol (20,23), the pharmacology and toxicology of these metabolites have not been extensively investigated or described. Only re- cently have the serious toxicological implications of these co- caine-alcohol metabolites become appreciated (10,11,14,15). Cocaethyiene (ethylbenzoylecgonine), a unique cocaine me- tabolite formed in both humans (5,6,10,12,14,19,33) and ani- mais (3,11,14,15,21) in the presence of ethyl alcohol, has been demonstrated to be more potent than cocaine in mediating lethality (11). Even more alarming is the recent report demon- strating the presence of cocaethyiene in the newborn of a co- caine-addicted mother (33). It is well documented that cocaine-mediated lethality in- volves components of both the central nervous system as well as the cardiovascular system (7,8,13,16,25,27,28). With re- spect to the central nervous system, preliminary studies indi- cate that cocaethylene has a pharmacological profile similar but not identical to cocaine (10). For example, cocaetliylene was equally potent in binding to the dopamine transporter but approximately 50-fold less potent in binding to the norepi- nephrine transport site (10). Although it was demonstrated that in the presence of cocaethylene individuals had significant increases in heart rate, cardiac output, and diastolic blood pressure (19), the direct adverse cardiovascular effects of co- caethylene remain to be investigated. Therefore, the purpose of this investigation was to define and describe an acute direct dose- and time-dependent toxicological prof'fle for cocaeth- ylene in an in vitro system of spontaneously contracting pri- mary myocardial cell cultures employing an acute exposure paradigm. METHODS Animal Selection Sprague-Dawiey rat pups were obtained from an in-house breeding colony established and maintained by the University of Oklahoma Health Sciences Center Animal Resources staff in accordance with the standards of the American Association for Accreditation of Laboratory Animal Care (AAALAC). The protocols were approved by the University of Oklahoma Institutional Animal Care and Use Committee (IACUC). All rats were exposed to a 12-h light/dark cycle with ad libitum access to standard laboratory chow. Cell Isolation Approximately 20-30 hearts were obtained from 3-5-day- old pups. Monolayer cell cultures were established by the Requests for reprints should be addressed to Allison A. Welder, Ph.D., College of Pharmacy, The University of Oklahoma Health Sciences Center, Department of Medicinal Chemistry and Pharmacodynamies, 1110 N. Stonewall, Oklahoma City, OK 73190. 285