Interaction between G protein-operated receptors eliciting secretion in rat adrenals

Álvarez, Consuelo Vélez; Lorenzo, Carmelo; Santana, Francisco J.; Borges, Ricardo

doi:10.1016/s0006-2952(96)00712-5

Cited by 8 publications

(8 citation statements)

References 33 publications

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“…3e-h), bradykinin and histamine [14]. These results are consistent with those reported previously [5,10]. Unlike PKC, PKA does not seem to downregulate receptor/G protein pathways.…”

Section: Modulation Of Secretory Responses By Activation Of Pka With supporting

confidence: 91%

“…Thus, the mode of modulation of secretory responses following activation of PKC seems to depend on secretagogues used for stimulation. However, the situation could be more complicated since unlike the above results, phorbol esters did not affect muscarine-or bradykinin-evoked secretion from rat chromaffin cells in some studies [4,5]. Disagreement of this sort is often found in the literature.…”

Section: Introductionmentioning

confidence: 72%

“…Arvarez et al [5] reported that PDBu potentiated the secretion evoked by high K + , did not change that evoked by bradykinin, and suppressed those evoked by muscarine, histamine and angiotensin II. High-K + -evoked secretion is expected to be potentiated as the result of the late-stage modulation since this secretory response does not depend on receptor/G protein pathways.…”

Section: Differential Modulation Of Secretory Responses Evoked By Varmentioning

confidence: 99%

“…In intact chromaffin cells, a variety of effects of phorbol esters on stimulant-evoked secretory responses have been reported. The treatment of the rat adrenal medulla with phorbol esters increased CA secretions evoked by nicotine [4], high K + [4,5] or bradykinin [6], but inhibited those evoked by muscarinic agents or histamine [5,6]. Thus, the mode of modulation of secretory responses following activation of PKC seems to depend on secretagogues used for stimulation.…”

Section: Introductionmentioning

confidence: 95%

“…Similarly, scattered results have been obtained in studies on modulatory effects of the activation of PKA by forskolin on secretory responses. Forskolin either increased [5,10,11] or decreased [12,13] stimulated secretions. These results imply that the protein kinases may affect multiple elements in the secretory processes, so that the modulation as a whole may be either facilitatory or inhibitory depending on signaling pathways used by respective stimulants and also on intracellular conditions when cells are stimulated.…”

Section: Introductionmentioning

confidence: 99%

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Modulations of Early and Late Secretory Processes by Activation of Protein Kinases in the Rat Adrenal Medulla

Warashina¹

1998

Neurosignals

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Modulatory effects of the activation of either protein kinase C (PKC) by phorbol 12,13-dibutyrate (PDBu) or protein kinase A (PKA) by forskolin on stimulant-evoked secretory processes in the perfused rat adrenal medulla were studied. PDBu or forskolin was applied during repetitive stimulation (30 s each at 10-min intervals) with nicotine, bradykinin, muscarine or histamine, and changes in [Ca²⁺]_i (fura-2 microfluorometry) and catecholamine secretions (electrochemical detection) were simultaneously measured. PDBu markedly potentiated the nicotine-evoked secretion without altering the [Ca²⁺]_i response. PDBu partially inhibited the muscarine-evoked secretion and almost completely blocked the histamine-evoked secretion, concomitantly with extensive suppressions of the [Ca²⁺]_i responses to these stimulants. The bradykinin-evoked secretion was enhanced by PDBu despite a slight attenuation of the [Ca²⁺]_i response. PDBu reduced bradykinin-induced intracellular Ca²⁺ release in a Ca²⁺-free medium but enhanced the secretion associated with the released Ca²⁺. These results suggest that PDBu-activated PKC modulates secretory processes at, at least, two different stages. An early-stage modulation may downregulate receptor/G protein systems, which accounts for the inhibitory effect of PDBu on the muscarine- and histamine-evoked responses. A late-stage modulation may generally promote Ca²⁺-triggered exocytosis after elevation of [Ca²⁺]_i, which explains the potentiation of the nicotine-evoked secretion by PDBu. The late-stage modulation may counteract the early-stage modulation in bradykinin-stimulated cells. Forskolin potentiated the secretory responses to the four secretagogues without increasing the [Ca²⁺]_i responses. PKA may modulate secretory process at a step(s) distal to the rise in [Ca²⁺]_i as is the case with the late-stage modulation by PKC.

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“…3e-h), bradykinin and histamine [14]. These results are consistent with those reported previously [5,10]. Unlike PKC, PKA does not seem to downregulate receptor/G protein pathways.…”

Section: Modulation Of Secretory Responses By Activation Of Pka With supporting

confidence: 91%

Section: Introductionmentioning

confidence: 72%

Section: Differential Modulation Of Secretory Responses Evoked By Varmentioning

confidence: 99%