TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto A1 - Krach, Christian A1 - Baumann, Arnd A1 - Blenau, Wolfgang T1 - The aminergic control of cockroach salivary glands N2 - The acinar salivary glands of cockroaches receive a dual innervation from the subesophageal ganglion and the stomatogastric nervous system. Acinar cells are surrounded by a plexus of dopaminergic and serotonergic varicose fibers. In addition, seroton-ergic terminals lie deep in the extracellulor spaces between acinar cells. Excitation-secretion coupling in cockroach salivary glands is stimulated by both dopamine and serotonin. These monoamines cause increases in the intracellular concentrations of cAMP and Ca2+. Stimulation of the glands by serotonin results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, two elementary secretary processes, namely electrolyte/water secretion and protein secretion, are triggered by different aminergic transmitters. Because of its simplicity and experimental accessibility, cockroach salivary glands have been used extensively as a model system to study the cellular actions of biogenic amines and to examine the pharmacological properties of biogenic amine receptors. In this review, we summarize current knowledge concerning the aminergic control of cockroach salivary glands and discuss our efforts to characterize Periplaneta biogenic amine receptors molecularly Y1 - 2006 UR - 1960 = Doi 10.1002/Arch.20128 ER - TY - JOUR A1 - Schewe, Bettina A1 - Schmaelzlin, Elmar A1 - Walz, Bernd T1 - Intracellular pH homeostasis and serotonin-induced pH changes in Calliphora salivary glands : the contribution of V-ATPase and carbonic anhydrase Y1 - 2008 ER - TY - JOUR A1 - Dames, Petra A1 - Zimmermann, Bernhard A1 - Schmidt, Ruth A1 - Rein, Julia A1 - Voss, Martin A1 - Schewe, Bettina A1 - Walz, Bernd A1 - Baumann, Otto T1 - cAMP regulates plasma membrane vacuolar-type H+-ATPase assembly and activity in blowfly salivary glands N2 - Reversible assembly of the V0V1 holoenzyme from V-0 and V-1 subcomplexes is a widely used mechanism for regulation of vacuolar-type H+-ATPases (V-ATPases) in animal cells. in the blowfly (Calliphora vicina) salivary gland, V- ATPase is located in the apical membrane of the secretory cells and energizes the secretion of a KCl-rich saliva in response to the hormone serotonin. We have examined whether the CAMP pathway, known to be activated by serotonin, controls V-ATPase assembly and activity. Fluorescence measurements of pH changes at the luminal surface of isolated glands demonstrate that CAMP, Sp-adenosine-3',5'-cyclic monophosphorothioate, or forskolin, similar to serotonin, cause V-ATPase-dependent luminal acidification. In addition, V-ATPase-dependent ATP hydrolysis increases upon treatment with these agents. Immunofluorescence microscopy and pelleting assays have demonstrated further that V, components become translocated from the cytoplasm to the apical membrane and V-ATPase holoenzymes are assembled at the apical membrane during conditions that increase intracellular cAMP. Because these actions occur without a change in cytosolic Ca2+, our findings suggest that the cAMP pathway mediates the reversible assembly and activation of V-ATPase molecules at the apical membrane upon hormonal stimulus Y1 - 2006 UR - http://www.pnas.org/ U6 - https://doi.org/10.1073/pnas.0600011103 SN - 0027-8424 ER - 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 SN - 0022-1910 ER - TY - JOUR A1 - Hille, Carsten A1 - Walz, Bernd T1 - Dopamine-induced graded intracellular Ca2+ elevation via the Na+-Ca2+ exchanger operating in the Ca2+-entry mode in cockroach salivary ducts N2 - Stimulation with the neurotransmitter dopamine causes an amplitude-modulated increase in the intracellular Ca2+ concentration ([Ca2+](i)) in epithelial cells of the ducts of cockroach salivary glands. This is completely attributable to a Ca2+ influx from the extracellular space. Additionally, dopamine induces a massive [Na+](i) elevation via the Na+- K+-2Cl(-) cotransporter (NKCC). We have reasoned that Ca2+-entry is mediated by the Na+-Ca2+ exchanger (NCE) operating in the Ca2+-entry mode. To test this hypothesis, [Ca2+](i) and [Na+](i) were measured by using the fluorescent dyes Fura- 2, Fluo-3, and SBFI. Inhibition of Na+-entry from the extracellular space by removal of extracellular Na+ or inhibition of the NKCC by 10 mu M bumetanide did not influence resting [Ca2+]i but completely abolished the dopamine-induced [Ca2+](i) elevation. Simultaneous recordings of [Ca2+](i) and [Na+](i) revealed that the dopamine-induced [Na+](i) elevation preceded the [Ca2+](i) elevation. During dopamine stimulation, the generation of an outward Na+ concentration gradient by removal of extracellular Na+ boosted the [Ca2+](i) elevation. Furthermore, prolonging the dopamine-induced [Na+](i) rise by blocking the Na+/K+-ATPase reduced the recovery from [Ca2+](i) elevation. These results indicate that dopamine induces a massive NKCC-mediated elevation in [Na+](i), which reverses the NCE activity into the reverse mode causing a graded [Ca2+](i) elevation in the duct cells. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/01434160 U6 - https://doi.org/10.1016/j.ceca.2005.11.006 SN - 0143-4160 ER - TY - JOUR A1 - Baumann, Otto A1 - Kühnel, Dana A1 - Dames, Petra A1 - Walz, Bernd T1 - Dopaminergic and serotonergic innervation of cockroach salivary glands : distribution and morphology of synapses and release sites N2 - The paired salivary glands in the cockroach are composed of acini with ion-transporting peripheral P-cells and protein-secreting central C-cells, and a duct system for the modification of the primary saliva. Secretory activity is controlled by serotonergic and dopaminergic neurons, whose axons form a dense plexus on the glands. The spatial relationship of release sites for serotonin and dopamine to the various cell types was determined by anti-synapsin immunofluorescence confocal microscopy and electron microscopy. Every C-cell apparently has only serotonergic synapses on its surface. Serotonergic and dopaminergic fibres on the acini have their release zones at a distance of similar to0.5 mum from the P-cells. Nerves between acinar lobules may serve as neurohaemal organs and contain abundant dopaminergic and few serotonergic release sites. Some dopaminergic and serotonergic release sites reside in the duct epithelium, the former throughout the duct system, the latter only in segments next to acini. These findings are consistent with the view that C-cells respond exclusively to serotonin, P-cells to serotonin and dopamine, and most duct cells only to dopamine. Moreover, the data suggest that C-cells are stimulated by serotonin released close to their surface, whereas P-cells and most duct cells are exposed to serotonin/dopamine liberated at some distance Y1 - 2004 ER - TY - JOUR A1 - Dames, Petra A1 - Schmidt, R. A1 - Walz, Bernd A1 - Baumann, Otto T1 - Regulation of vacuolar-type H+-ATPase (vATPase) in blowfly salivary glands Y1 - 2004 SN - 0171-9335 ER - TY - JOUR A1 - Marg, S. A1 - Walz, Bernd A1 - Blenau, Wolfgang T1 - The effects of dopamine receptor agonists and antagonists on the secretory rate of cockroach (Periplaneta americana) salivary glands N2 - The acinar salivary glands of the cockroach, Periplaneta americana, are innervated by dopaminergic and serotonergic nerve fibers. Serotonin stimulates the secretion of protein-rich saliva, whereas dopamine causes the production of protein-free saliva. This suggests that dopamine acts selectively on ion-transporting peripheral cells within the acini and the duct cells, and that serotonin acts on the protein-producing central cells of the acini. We have investigated the pharmacology of the dopamine-induced secretory activity of the salivary gland of Periplaneta americana by testing several dopamine receptor agonists and antagonists. The effects of dopamine can be mimicked by the non-selective dopamine receptor agonist 6,7-ADTN and, less effectively, by the vertebrate D1 receptor-selective agonist chloro-APB. The vertebrate D1 receptor-selective agonist SKF 38393 and vertebrate D2 receptor-selective agonist R(-)- TNPA were ineffective. R(+)-Lisuride induces a secretory response with a slower onset and a lower maximal response compared with dopamine-induced secretion. However, lisuride-stimulated glands continue secreting saliva, even after lisuride-washout. Dopamine-induced secretions can be blocked by the vertebrate dopamine receptor antagonists cis(Z)- flupenthixol, chlorpromazine, and S(+)-butaclamol. Our pharmacological data do not unequivocally indicate whether the dopamine receptors on the Periplaneta salivary glands belong to the D1 or D2 subfamily of dopamine receptors, but we can confirm that the pharmacology of invertebrate dopamine receptors is remarkably different from that of their vertebrate counterparts. (C) 2004 Elsevier Ltd. All rights reserved Y1 - 2004 SN - 0022-1910 ER - TY - JOUR A1 - Schmidt, R. A1 - Walz, Bernd T1 - Serotonin and histamine produce different spatiotemporal Ca2+ signals in blowfly salivary glands Y1 - 2004 SN - 0171-9335 ER - TY - JOUR A1 - Zimmermann, Bernhard A1 - Dames, Petra A1 - Walz, Bernd A1 - Baumann, Otto T1 - Distribution and serotonin-induced activation of vacuolar-type H+-ATPase in the salivary glands of the blowfly Calliphora vicina Y1 - 2003 ER -