COCULTURES OF ADULT VENTRICULAR MYOCYTES WITH STELLATE GANGLIA OR INTRINSIC CARDIAC NEURONS FROM GUINEA-PIGS - SPONTANEOUS ACTIVITY AND PHARMACOLOGICAL PROPERTIES

Objective: The aim was to develop long term primary cocultures of adul t ventricular myocytes with autonomic neurones dissociated from stella te or intrinsic cardiac ganglia. This was to provide an experimental m odel for the investigation of the regulatory role of autonomic neurone s with respect to cardiac myocyte function. Methods: Ventricular myocy tes and stellate and intrinsic cardiac neurones were enzymatically dis sociated from adult male guinea pigs and plated together on 13 mm cove r slips; the cultures were maintained in an incubator for two to 10 we eks. The electrical properties of cultured myocytes and neurones were investigated by means of a conventional microelectrode technique and t he spontaneous contractile activity of the myocytes was recorded by a video system. The electrical, contractile, and pharmacological propert ies of myocyte-neuronal networks were investigated by superfusing the cultures with various neuromodulators and blockers. Results: The elect rical properties of the cultured myocytes and neurones were similar to those reported in other in vitro studies. Innervated and non-innervat ed cardiomyocyte cultures responded differently, however, to various p harmacological interventions. Spontaneous contractions were attenuated by tetrodotoxin (4X10(-7) M), beta adrenergic blockade, and nicotinic blockade more in cocultures than in cardiac myocyte cultures alone. O n the other hand, the beta agonist isoproterenol increased the spontan eous beating in both types of cocultures more than in myocytes alone. The effects of the muscarinic agonist bethanechol and the muscarinic b locker atropine were not significantly different in innervated and non -innervated cultures. Nicotine induced either an increase or decrease in contractile rates of both cocultures and did not affect non-innerva ted myocyte cultures. Conclusions: Cocultures of myocytes and autonomi c neurones alter the responses of myocytes relative to cultures withou t neurones. The results suggest that functional contacts can be establ ished between adult myocytes.and dissociated neurones in primary cultu res. Contractile rates of such myocyte cultures are influenced by the presence of neurones. Neurones innervating these cultures were modifie d by beta adrenergic, muscarinic, and nicotinic