The relationship between secretion of respiratory mucous glycoprotein from feline airways in organ culture and the intracellular activation of protein kinase C (PKC) and has been studied using a variety of PKC activators including phorbal myristrate acetate, mezerin and O-A-G as well as inhibitors including W-7 and H-7, PMA and Mezerin have a profound stimulatory effect on acid precipitable glycoprotein release. This effect is partially inhibited by H-7. The PMA effect is also partially inhibited by the PKC inhibitor sphingosine. It is also partially by the lipoxygenase pathway inhibitor NDGA or by the 5 lipoxygenase inhibitor L651.392. It is hoped that these studies will aid in the understanding of receptor-secretion coupling and provide insights into how to limit stimulated secretion in human airways. This project was expanded to investigate cellular mechanisms of secretion using a respiratory epithelial cell line. PKC actuation alone did not stimulate erocytasis at 30 minutes. However, PKC inhibitors did inhibit platelet activating factor (PAF) induced exocytosis of airway mucins. PAF stimulation of airway epithelial cells was associated with measurable activation of PKC. PKC isozymes were identified by antibody and then was evidence of translocation of PKC zeta. A manuscript is in press. This project has provided insight into the mechanism of secretory cell exocytosis.
