Iptakalim as a human nicotinic acetylcholine receptor antagonist.

Nicotinic acetylcholine receptors (nAChRs) play many critical roles in nervous system function and have been implicated in a variety of diseases. Drugs acting at nAChRs, perhaps in nAChR subtype-selective manners, can be used to dissect receptor function and perhaps as medications. In the present study, we used patch-clamp whole-cell recording and pharmacological manipulations to evaluate effects of iptakalim hydrochloride (Ipt), which is a drug reported to act as an ATP-sensitive potassium (K(ATP)) channel opener, on selected human nAChRs heterologously expressed in the native nAChR-null SH-EP1 human epithelial cell line.

Heterologous expression of human {alpha}6{beta}4{beta}3{alpha}5 nicotinic acetylcholine receptors: binding properties consistent with their natural expression require quaternary subunit assembly including the {alpha}5 subunit.

Heterologous expression and lesioning studies were conducted to identify possible subunit assembly partners in nicotinic acetylcholine receptors (nAChR) containing alpha6 subunits (alpha6(*) nAChR). SH-EP1 human epithelial cells were transfected with the requisite subunits to achieve stable expression of human alpha6beta2, alpha6beta4, alpha6beta2beta3, alpha6beta4beta3, or alpha6beta4beta3alpha5 nAChR. Cells expressing subunits needed to form alpha6beta4beta3alpha5 nAChR exhibited saturable [(3)H]epibatidine binding (K(d) = 95.

Extensive eosinophil degranulation and peroxidase-mediated oxidation of airway proteins do not occur in a mouse ovalbumin-challenge model of pulmonary inflammation.

Paradigms of eosinophil effector function in the lungs of asthma patients invariably depend on activities mediated by cationic proteins released from secondary granules during a process collectively referred to as degranulation. In this study, we generated knockout mice deficient for eosinophil peroxidase (EPO) to assess the role(s) of this abundant secondary granule protein in an OVA-challenge model. The loss of EPO had no effect on the development of OVA-induced pathologies in the mouse.

Mouse eosinophil-associated ribonucleases: a unique subfamily expressed during hematopoiesis.

A unique family of ribonucleases was identified by exhaustive screening of genomic and cDNA libraries using a probe derived from a gene encoding a ribonuclease stored in the mouse eosinophil secondary granule. This family contains at least 13 genes, which encode ribonucleases, and two potential pseudogenes. The conserved sequence identity among these genes (approximately 70%), as well as the isolation/purification of these ribonucleases from eosinophil secondary granules, has led us to conclude that these genes form a unique clade in the mouse that we have identified as the Ear (Eosinophil-associated ribonuclease) gene family.