Chronic cholinergic stimulation of canine respiratory tissue. Its effect on the activities of glycosyltransferases and release of macromolecules.

Abstract

The influence of cholingergic stimulation on the incorporation of D-[6-3H]glucosamine into macromolecules released by canine trachea in vitro, and the capacity of subcellular fraction of this tissue to catalyze the transfer of various sugars to specific glycoproteins were measured. Canine trachea was incubated with radiohexosamine for 18 hours in the presence of methacholine chloride. The [3H]macromolecules subsequently released were fractionated on columns of 1 per cent agarose. Those macromolecules eluted from the columns with a mobility identical to that of large molecular weight, mucin-type glycoproteins of canine tracheal pouch secretions collected in vivo were increased. The tissue then did not respond to further challenges with acetylcholine chloride, at least as regards the release of radiomacromolecular. In addition, in vitro challenges of methacholine chloride failed to alter the specific activities of the tracheobronchial tissue glycosyltransferases. The specific activities of 2 galactosyltransferases, a sialytransferase, and an N-acetylgalactosaminyltransferase were elevated after 1 month and after 2 months of daily subcutaneous injections of methacholine chloride. No further increases were seen during the third month of injections; throughout the 3 months, the specific activity of fucosyltransferase failed to change.