分离大鼠胰腺腺泡细胞中对钙离子／钙调素依赖性蛋白激酶Ⅱ的M—型胆碱能激活

Muscarinic stimulation of calcium/calmodulin-dependent protein kinase II in isolated rat pancreatic acini.

AIM: To study whether M3 receptor occupation would lead to activation of calcium/calmodulin-dependent protein kinase II (CaM kinase II). METHODS: In this study, we isolated rat pancreatic acini by collagenase digestion; measured the Ca2+/calmodulin-independent activity of autophosphorylated form of the CaM kinase II both before and after stimulation of the acini with muscarinic secretagogue bethanechol (Bet). RESULTS: Bet stimulated the activation of, or generation of Ca(2+)-independent activity of, this kinase, in a concentration (0.0001-1 mmol.L-1) and time (5-300 s)-dependent manner; with Bet of 100 mumol.L-1, Ca(2+)-independent activity increased from an unstimulated level of 4.5 +/- 0.3 (n = 4) to 8.9 +/- 1.3 (n = 4, P < 0.05) at 5 s. Another Ca2+ mobilizing secretagogue cholecystokinin (CCK) also activated the kinase; at 1 mumol.L-1, CCK increased Ca(2+)-independent kinase activity to 12.9 +/- 0.5 (n = 6, P < 0.05). Vasoactive intestinal peptide (VIP) at 1 mumol.L-1 did not produce significant Ca(2+)-independent kinase activity (from control 3.90 +/- 0.28 to 4.53 +/- 0.47, n = 6, P > 0.05). Atropine completely blocked Bet activation of the kinase. CONCLUSION: CaM kinase II plays a pivotal role in digestive enzyme secretion, especially during the initial phase of amylase secretion.