Multiple signaling pathways control stimulus-secretion coupling in rat peritoneal mast cells.

Abstract

Fura-2 and membrane capacitance measurements were performed to investigate intracellular Ca2+ concentration ((Ca2+J1)

Dual effects of G‐protein activation on Ca‐dependent exocytosis in bovine lactotrophs

“…The inhibitory role is suggested by the suppression of the relative Cm increase (secretory response) by G-protein activation, whereas the stimulatory role is indicated by the faster kinetics of Cm increase indicating more rapid granule translocation. Our results are thus in agreement with mounting evidence that multiple pathways with several functionally different G-proteins are involved in the dynamic control of stimulussecretion coupling [28]. The two functionally distinct roles of G-proteins demonstrated by the present experiments may thus be important in prolactin secretion controlled by dopamine and TRH (thyrotrophin releasing hormone): evidence suggests that both of these substances are linked to intracellular pathways via G-proteins [1][2][3][4][5][6].…”

Differential Roles of CB1 and CB2 Cannabinoid Receptors in Mast Cells

“…CB1 activity through G i -G o coupling will tend to decrease cAMP levels. It is established that global elevations in cAMP (via AC activation or cytosolic perfusion) tend to suppress basal secretory responses (57,58). Hence, CB1/G i/o signals would be expected to be neutral or to enhance serotonin release.…”

Synergistic effects of calcium‐mobilizing agents and adenosine on histamine release from rat peritoneal mast cells

“…This dependence of the response to adenosine and its analogues on the level * of stimulation is a likely explanation for the large variations of its EC5o value and the flat concen-* tration-response curves when a large number of experiments are averaged, which has been found by various workers (Marquardt et al, 1978;Holgate et al, 1980;Welton & Simko 1980;Church et al, 1986). There are several reports in the literature that calcium may not alone be responsible for the mediation of secretory responses (see Gomperts, 1986, andPenner, 1988, for reviews). Our data presented here and in previous papers (Lohse et al, 1987;1988) 40 50…”

“…This washing step was repeated once and the cells resuspended in incubation buffer (= washing buffer supplemented with 1 M CaCl2 and 0.5mm MgCl2), giving a suspension of about 2 x 10o mast cells per ml. It has been shown previously that the effects of adenosine on histamine release are indistinguishable in crude mast cell preparations and in cells purified to >95% homogeneity (Lohse et al, 1987;1988).…”

“…However, there is increasing evidence that an elevation of intracellular calcium within the physiological range is not sufficient to trigger mast cell mediator release (Neher & Almers, 1986). Consequently, additional signalling pathways have been postulated that act in concert with intracellular calcium (Beaven et al, 1987;Penner & Neher, 1988;Penner, 1988). In a recent study we identified adenosine as a candidate for such a pathway which acts ' Author for correspondence.…”