Calcium influx through 'L'-type channels into rat anterior pituitary cells can be modulated in two ways by protein kinase C (PKC-isoform selectivity of 1,2-dioctanoyl sn-glycerol?).
The depolarisation-induced influx of 45Ca2+ into anterior pituitary tissue and GH3 cells through 'L'-type, nimodipine-sensitive channels was investigated. In anterior pituitary prisms, phorbol esters, activators of protein kinase C, caused an enhancement of K(+)-induced 45Ca2+ influx. However, in the GH3 anterior pituitary cell line, phorbol esters inhibited K(+)-induced 45Ca2+ influx. The modulation by phorbol esters in both tissues was stereo-specific and time- and concentration-dependent. The diacylglycerol analogue, 1,2-dioctanoyl sn-glycerol was able to mimic the phorbol ester-induced enhancement of calcium influx into anterior pituitary pieces, but was ineffective in GH3 cells. 1,2-Dioctanoyl sn-glycerol may selectively activate an isoform of protein kinase C which is responsible for enhanced 'L'-type Ca(2+)-channel activity.
MacEwan
D J
DJ
MRC Brain Metabolism Unit, Edinburgh, UK.
Mitchell
R
R
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002460:Cell Line; D004075:Diglycerides / Q000378:metabolism*; D004789:Enzyme Activation; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D015220:Calcium Channels; D004075:Diglycerides; C044295:1,2-dioctanoylglycerol; D011493:Protein Kinase C; D002118:Calcium