TY  - JOUR
A1  - Rietdorf, Katja
A1  - Blenau, Wolfgang
A1  - Walz, Bernd
T1  - Protein secretion in cockroach salivary glands requires an increase in intracellular cAMP and Ca2+ concentrations
N2  - The salivary glands in the cockroach Periplaneta americana secrete protein-containing saliva when stimulated by serotonin (5-HT) and protein-free saliva upon dopamine stimulation. In order to obtain information concerning the signalling pathways involved in 5-HT-induced protein secretion, we have determined the protein content of saliva secreted after experimental manipulations that potentially elevate intracellular Ca2+ and cyclic nucleotide concentrations in isolated glands. We have found that 5-HT stimulates the rate of protein secretion in a dose-dependent manner (threshold: 3 x 10(-8) M; EC50 1.5 x 10(-6) M). The maximal rate of 5-HT-induced protein secretion was 2.2 +/- 0.2 mu g/min. Increasing intracellular Ca2+ or cAMP by bath application of ionomycin (5 mu M), db cAMP (10 mM), forskolin (100 mu M) or IBMX (100 mu M), respectively, stimulated protein secretion at significantly lower rates, whereas db cGMP (1 mM) did not activate protein secretion. The high rates and the kinetics of 5-HT-induced protein secretion could only be mimicked by either applying forskolin together with IBMX (with or without ionomycin) or by applying IBMX together with ionomycin. Our measurements suggest that 5-HT-induced protein secretion is mediated by an elevation of [cAMP](i) and that Ca2+ may function as a co-agonist and augment the rate of protein secretion. (c) 2005 Elsevier Ltd. All rights reserved
Y1  - 2005
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/13850
SN  - 0022-1910
ER  -