Effects of cocaine and norepinephrine on primary cultures of neonatal rat myocardial cells.

Sudden cardiac death associated with cocaine (Coc) abuse in healthy, physically active individuals became a grave concern in the late 1980s. It is well documented that physical activity increases circulating plasma catecholamine levels. Catecholamines as well as Coc are independently capable of inducing toxic cardiac effects. The purpose of this investigation was to evaluate the synergistic or additive toxic effects of norepinephrine (NE) and Coc in primary myocardial cell cultures obtained from 3- to 5-d-old Sprague-Dawley rats. Alterations in lactate dehydrogenase release (LDH), lysosomal neutral red retention (NR), beating activity, and morphology were evaluated after treatment of the cells for 1-24 h with 1 x 10(-3) M Coc alone, 1 x 10(-5) M Coc alone, 1 x 10(-5) M NE alone, 1 x 10(-3) M Coc with 1 x 10(-5) M NE, or 1 x 10(-5) M Coc with 1 x 10(-5) M NE. LDH release was elevated significantly after 24 h only with those cells exposed to 1 x 10(-3) M Coc alone and 1 x 10(-3) M Coc + 1 x 10(-5) M NE. Using NR retention as a score for lysosomal treatment of the cells with 1 x 10(-5) M Coc and 1 x 10(-3) M Coc alone did not decrease dye retention significantly. However, 1 x 10(-5) M NE combined with 1 x 10(-3) M Coc significantly reduced lysosomal dye retention as early as 1 h after treatment. After 24 h, 1 x 10(-5) M NE alone and 1 x 10(-5) M NE combined with 1 x 10(-5) M Coc significantly increased lysosomal fragility. Beating activity was altered in all treatment groups. Contractile activity was slow and irregular or completely absent with 1 x 10(-5) and 1 x 10(-3) M Coc, respectively. When NE (1 x 10(-5) M) was combined with both concentrations of Coc, there was distinct focalization of sharp, rapid contractions within the cells, which were asynchronous and/or arrhythmic in nature. Those cells exposed to 1 x 10(-5) M NE with 1 x 10(-5) M Coc for 24 h appeared hypercontracted with marked pseudopodia and cytoplasmic granule formation distinctly different from that exhibited by the cells exposed to 1 x 10(-5) M Coc alone. These data demonstrate that NE potentiates the adverse effects of Coc on contractile activity and morphology of spontaneously contracting neonatal myocardial cells maintained in culture.

Effects of nitrendipine on cocaine-induced toxicity evaluated in primary myocardial cell cultures.

Currently, there is no uniform treatment for abnormal cardiac events precipitated by cocaine use. However, clinical strategies include use of calcium channel antagonists for cardiovascular emergencies. In experimental situations using rats, simultaneous administration of nitrendipine (NIT) with cocaine to the whole animal (1.46 x 10(-3) mg/kg/min of NIT; 2 mg/kg/min of cocaine) and isolated retrograde perfused hearts (Langendorff; 1 x 10(-7) M NIT; 1 x 10(-7) to 1 x 10(-4) M cocaine) normalized cocaine-induced abnormalities in heart rhythm and provided protection from acute cocaine-induced morphological lesions. Using similar concentrations of NIT and cocaine, the purpose of this study was to evaluate the direct cardiac cellular effects of NIT on cocaine-induced alterations in beating activity, morphology, and lactate dehydrogenase (LDH) release in a controlled in vitro system of primary myocardial cell cultures. Cultures were established from hearts of 3-5-day-old Sprague-Dawley rats. After the cells had been maintained in culture for 4 days, evaluation of drug effects were made with exposure to 1 x 10(-3) and 1 x 10(-5) M cocaine alone and combinations of these two concentrations of cocaine with simultaneous exposure to 1 x 10(-7) M NIT for 1 to 24 h. Those cells exposed to 1 x 10(-5) M cocaine alone maintained some beating activity after 1, 4, and 24 h. Beating activity was significantly depressed after treatment with 1 x 10(-3) M cocaine alone and with both combinations of cocaine and NIT. Morphological integrity was maintained in all treatment groups for 1 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the combined toxic effects of cocaine and ethanol on primary myocardial cell cultures.

Since 1978, the most prevalent drug used in conjunction with cocaine in cocaine-associated myocardial deaths is ethanol. Primary myocardial cell cultures were used to evaluate the acute additive cardiotoxic effects of cocaine and ethanol. The cultures were exposed to 1 x 10(-3)m or 1 x 10(-5)m-cocaine or combinations of both concentrations of cocaine with 600 mg ethanol/100 ml. Alterations in beating activity, morphology, and lactate dehydrogenase (LDH) release were evaluated after 1, 4 and 24 hr of treatment. Although cells exposed to 1 x 10(-5)m-cocaine or to 1 x 10(-5)m-cocaine and ethanol were able to retain some beating activity, no beating activity occurred in cells exposed to 1 x 10(-3)m-cocaine with or without ethanol. Morphologically, pseudopodia and disruption of the monolayer were more extensive in cells treated for 4 or 24 hr with the combinations of cocaine and ethanol in comparison with those treated with cocaine alone. After 24 hr, LDH release in cells exposed to 1 x 10(-3)m-cocaine or 1 x 10(-3)m-cocaine with ethanol was elevated over the level in untreated controls. These data suggest that ethanol enhances cocaine-induced beating abnormalities and morphological alterations in primary myocardial cell cultures.