Acetylcholine and ATP are excitatory cotransmitters in parasympathetic nerves. We used P2X 1 receptor antagonists to further characterize the purinergic component of neurotransmission in isolated detrusor muscle of guinea pig urinary bladder. In the presence of atropine (1 M) and prazosin (100 nM), pyridoxalphosphate-6-azophenyl-2Ј,4Ј-disulfonic acid (PPADS) (0.1-100 M) and suramin (1-300 M) inhibited contractions evoked by 4 Hz nerve stimulation in a concentration-dependent manner (IC 50 of 6.9 and 13.4 M, respectively). Maximum inhibition was 50 -60%, which was unaffected by coadministration of the ectonucleotidase inhibitor ARL67156

A non-neuronal cholinergic system that includes neuronal-like nicotinic acetylcholine receptors (nAChRs) has recently been described in epithelial cells that line the skin and the upper respiratory tract. Since the use of nicotine-containing products is associated with morbidity in the upper digestive tract, and since nicotine may alter cellular functions directly via nAChRs, we sought to identify and characterize a non-neuronal cholinergic system in the gingival and esophageal epithelia. mRNA transcripts for alpha3, alpha5, alpha7, and beta2 nAChR subunits, choline acetyltransferase, and the asymmetric and globular forms of acetylcholinesterase were amplified from gingival keratinocytes (KC) by means of polymerase chain-reactions. These proteins were visualized in the gingival and esophageal epithelia by means of specific antibodies. Variations in distribution and intensity of immunostaining were found, indicating that the repertoire of cholinergic enzymes and receptors expressed by the cells changes during epithelial maturation, and that an upward concentration gradient of free acetylcholine exists. Blocking of the nAChRs with mecamylamine resulted in reversible loss of cell-to-cell adhesion, and shrinking and rounding of cultured gingival KC. Activation of the receptors with acetylcholine or carbachol caused stretching and peripheral ruffling of the cytoplasmic aprons, and formation of new intercellular contacts. These results demonstrate that both the keratinizing epithelium of attached gingiva and the non-keratinizing epithelium lining the upper two-thirds of the esophageal mucosa possess a non-neuronal cholinergic system. The nAChRs expressed by these epithelia are coupled to regulation of cell adhesion and motility, and may provide a target for the deleterious effects of nicotine.

A middle-aged woman with neutropenia and ataxia was found to have raised plasma zinc and profoundly low plasma copper concentrations. When found that she had been prescribed 135 mg zinc/day for seven years, a diagnosis of zinc-induced copper deficiency was made. After the zinc prescription was stopped, her copper and zinc concentrations and neutropenia normalized but she only had partial improvement in neurological status. The diagnosis of zinc-induced copper deficiency can be facilitated by the laboratory through measurement of plasma zinc concentration in patients with a low plasma copper concentration.