Expression and function of neuronal nicotinic acetylcholine receptors in rat microvascular endothelial cells

Physiol 286: H486–H491, 2004. First published September 25, 2003; 10.1152/ajpheart.00620.2003.—The expression and function of nico-tinic ACh receptors (nAChRs) in rat coronary microvascular endo-thelial cells (CMECs) were examined using RT-PCR and whole cell patch-clamp recording methods. RT-PCR revealed expression of mRNA encoding for the subunits 2, 3, 4, 5, 7, 2, and 4 but not 3. Focal application of ACh evoked an inward current in isolated CMECs voltage clamped at negative membrane potentials. The cur-rent-voltage relationship of the ACh-induced current exhibited marked inward rectification and a reversal potential (Erev) close to 0 mV. The cholinergic agonists nicotine, epibatidine, and cytisine acti-vated membrane currents similar to those evoked by ACh. The nicotine-induced current was abolished by the neuronal nAChR an-tagonist mecamylamine. The direction and magnitude of the shift in Erev of nicotine-induced current as a function of extracellular N