QUALITATIVE IMMUNOBLOT ANALYSIS OF PKC ISOFORMS EXPRESSED IN AIRWAY SMOOTH-MUSCLE

Protein kinase C (PKC) was originally identified as a single serine/th reonine protein kinase with calcium- and phospholipid-dependent activi ty, but more recently PKC has been found to consist of a family of mul tiple isoenzymes with different biochemical characteristics, substrate s, and cofactor requirements. PKC is particularly important in regulat ing airway smooth muscle (ASM) tone. Although a previous investigation has demonstrated PKC-beta, -delta, -epsilon, -theta and -zeta in cani ne trachealis muscle, additional PKC isoforms have not been characteri zed in ASM. Therefore, immunoblot analysis using nine isotype-specific antibodies was used to further characterize the expression of PKC iso forms in porcine ASM. In addition to the previously described beta-, d elta-, epsilon-, and zeta-isoforms in ASM, the calcium-dependent alpha -isoform, and the calcium- and diacylglycerol-independent isoforms iot a/lambda and mu were identified. This study demonstrates multiple PKC isoforms in porcine ASM that can participate in intracellular signalin g pathways in this tissue.