Positive inotropic and chronotropic effects of the calcium ionophore A23187 (calimycin) on guinea-pig atria

1988 ◽  
Vol 83 (2) ◽  
pp. 167-175 ◽  
Author(s):  
H. M. Himmel ◽  
M. Siess
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Chronotropic Effects ◽  
Guinea Pig Atria

scholarly journals Cross-regulation of cortisol secretion by adrenocorticotropin and platelet-activating factor in perfused guinea pig adrenals

2007 ◽  
Vol 195 (1) ◽  
pp. 29-38
Author(s):  
Toshio Shimada ◽  
Taeko Hirose ◽  
Itsuro Matsumoto ◽  
Tadaomi Aikawa
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Cortisol Response ◽  
Cortisol Secretion ◽  
Induced Signal ◽  
Dependent Processes

We examined the cross-regulation of signaling between ACTH-and platelet-activating factor (PAF)-mediated steroidogenesis in the perfused guinea pig adrenal gland. Our method of in situ perfusion using an artificial medium can evaluate whether cortisol secretion in response to ACTH and PAF is interactive. Treating adrenal glands with 100 pg/ml ACTH diminished the subsequent cortisol response to 10 nM PAF. By contrast, PAF resulted in subsequent potentiation of ACTH-induced cortisol secretion. A mixture of 50 μM l-α-1-oleoyl-2-acetyl-sn-glycerol (OAG), an activator of protein kinase C (PKC), and 3.3 μM calcium ionophore (A23187), or 10 μM forskolin (FRK) diminished the cortisol response to PAF, whereas that to ACTH was unaffected. Each of PAF, ACTH, or FRK eliminated the cortisol response to OAG plus A23187, whereas that to FRK was unaffected. These data show that the protein kinase A (PKA)-dependent processes activated by ACTH or FRK can interfere with PAF-induced signal transduction at receptor and post-receptor levels. In contrast, PKC-dependent processes activated by PAF promoted ACTH-signaling at receptor and post-receptor level. Cross-regulation between processes activated by PAF receptor–PKC and by ACTH receptor–PKA might function in the multifactorial regulation of adrenocortical steroidogenesis.

The calcium ionophore A23187 stimulates glycoprotein secretion by the guinea pig gallbladder

Hepatology ◽  
1986 ◽  
Vol 6 (4) ◽  
pp. 569-573 ◽  
Author(s):  
Peter F. Malet ◽  
Catherine L. Locke ◽  
Bruce W. Trotman ◽  
Roger D. Soloway
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Glycoprotein Secretion

scholarly journals Platelet-activating factor acts on cortisol secretion by perfused guinea-pig adrenals via calcium-/phospholipid-dependent mechanisms

2005 ◽  
Vol 184 (2) ◽  
pp. 381-391 ◽  
Author(s):  
Toshio Shimada ◽  
Taeko Hirose ◽  
Itsuro Matsumoto ◽  
Tadaomi Aikawa
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Breakdown Product ◽  
Ionophore A23187 ◽  
Cortisol Secretion ◽  
Cortisol Responses ◽  
Paf Receptor

Bilateral adrenals of the guinea pig were perfused in situ with an artificial medium equilibrated with 95% O2/5% CO2. Platelet-activating factor (PAF) induced biphasic cortisol responses, which reached a maximum at 10 nM PAF and declined at 100 nM. The effect of the PAF receptor antagonists CV-3988 and CV-6209 on PAF-stimulated cortisol secretion was examined. Prior exposure of adrenal glands to 10 μM CV-3988 or a simultaneous incubation with 10 μM CV-6209 abolished the cortisol response to 10 nM PAF. Lyso-PAF (a PAF precursor and breakdown product) did not affect cortisol secretion. Concentrations of 5–12.5 μM 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), a protein kinase C (PKC) inhibitor, abolished subsequent cortisol secretion in response to 10 nM PAF. N-[2-(Methylamino)ethyl]-5-isoquinoline sulfonamide dihydrochloride (H-8), a protein kinase A inhibitor, was less effective. A calcium ionophore (A23187) at 3.3 and 10 μM increased cortisol secretion, but the activator of PKC, l-α-1-oleoyl-2-acetyl-sn-3-glycerol (OAG), at 50 μM had no effect. When infused simultaneously, OAG (50 μM) and A23187 (3.3 μM) stimulated cortisol secretion synergistically. The secretory response of cortisol to repeated infusions of adrenocortico-trophin (100 pg/ml) or forskolin (10 μM) was essentially reproducible. By contrast, cortisol secretion in response to repeated infusions of PAF (10 nM) or OAG plus A23187 was not reproducible and the second response was diminished compared with the first. Our findings suggest that PAF plays a role in the regulation of steroidogenesis via a mechanism mediated by the PAF receptor and PKC.

scholarly journals Characterization of the megakaryocyte secretory response: studies of continuously monitored release of endogenous ATP

Blood ◽  
1983 ◽  
Vol 61 (5) ◽  
pp. 967-972 ◽  
Author(s):  
JL Miller
Keyword(s):  
Guinea Pig ◽  
Blood Platelets ◽  
Atp Release ◽  
Chemical Properties ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Storage Pool ◽  
Functional Aspects ◽  
Absolute Requirement

Abstract Megakaryocytes share a number of structural and chemical properties with their progeny, blood platelets. With the availability of highly purified preparations of megakaryocytes isolated from guinea pig bone marrow, it is now also possible to study functional aspects of these cells. The present work reports the first study of the release of endogenously stored materials in megakaryocytes. Guinea pig megakaryocytes isolated to 75%-90% purity were exposed to thrombin or calcium ionophore (A23187) and the release of ATP was continuously monitored with the luciferin-luciferase reaction. Both maximal extent and initial rate of release were studied. Thrombin-induced release was half-maximal at thrombin concentrations of 0.2–0.5 NIH U/ml. At 4 U/ml thrombin, maximal release was 538 +/- 147 nmole ATP/10(9) megakaryocytes. A23187 induced half-maximal responses at concentrations of 7–8 microM. ATP release by ionophore showed a nearly absolute requirement for extracellular calcium, with release by thrombin showing only a partial calcium dependence. Following overnight culture, the response to thrombin was unchanged, whereas ATP release in response to ionophore was consistently increased (p less than 0.01). By comparison of maximally releasable ATP with total cellular ATP content, the storage pool of ATP in megakaryocytes was determined to comprise only 2%-6% of total megakaryocyte ATP, in contrast to an ATP storage pool of 20%-30% in guinea pig platelets. This difference may reflect further entry of ATP into the storage pool compartment or an enhanced ability of the cell to recognize and respond fully to platelet stimuli as the megakaryocyte reaches full maturity.

Prostaglandin-induced pepsinogen secretion from dispersed gastric glands from guinea pig stomach

1985 ◽  
Vol 249 (5) ◽  
pp. G592-G598 ◽  
Author(s):  
S. Berger ◽  
J. P. Raufman
Keyword(s):  
Guinea Pig ◽  
Incubation Temperature ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Gastric Glands ◽  
Cellular Calcium ◽  
Pepsinogen Secretion ◽  
Carbonyl Cyanide ◽  
Guinea Pig Stomach

We examined the actions of several prostaglandins (PG) on pepsinogen secretion from dispersed gastric glands prepared from guinea pig stomach. Pepsinogen secretion was stimulated by PGA1, PGA2, PGB2, PGE1, and PGE2. PGE1 and PGE2 were 10 times more potent than PGA1 and PGA2. Reducing the incubation temperature from 37 degrees to 4 degrees C or adding carbonyl cyanide m-chlorophenylhydrazone reduced PG-stimulated pepsinogen secretion. PGE2-induced pepsinogen secretion was not altered by atropine or dibutyryl cGMP. Potentiation of pepsinogen secretion occurred with PGE2 plus carbachol or the calcium ionophore A23187 but not with PGE2 plus secretin or 8-bromo-cAMP. Isobutylmethylxanthine increased the potency and the efficacy of the action of PGE2 on pepsinogen secretion. These results indicate that PGE1, PGA2, PGB2, PGE1, and PGE2 can modulate pepsinogen secretion from dispersed gastric glands from guinea pig stomach. Moreover, potentiation of pepsinogen secretion occurs when PGE2 is combined with secretagogues whose actions appear to be mediated by changes in cellular calcium (carbachol and A23187) but not with secretagogues whose actions appear to be mediated by changes in cellular cAMP (secretin and 8-bromo-cAMP). These data suggest that PG-induced pepsinogen secretion may be mediated by changes in cellular cAMP.

Distinct activation of Na+-H+ exchange by gastrin and CCK peptide in acini from guinea pig

1988 ◽  
Vol 254 (1) ◽  
pp. G25-G32
Author(s):  
M. J. Bastie ◽  
M. Delvaux ◽  
M. Dufresne ◽  
J. S. Saunier-Blache ◽  
N. Vaysse ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Calcium Concentration ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Pancreatic Acini ◽  
Cck Receptors ◽  
Kinase C ◽  
22Na Uptake ◽  
Cck Antagonists

The effect of cholecystokinin (CCK)-gastrin family peptides (caerulein, unsulfated gastrin-17, and pentagastrin) and secretin in activating amiloride-sensitive 22Na uptake were investigated in guinea pig pancreatic acini. Secretin had no effect, but CCK-gastrin peptides stimulated the amiloride-sensitive 22Na uptake. The effect of caerulein was inhibited by dibutyryl guanosine 3',5'-cyclic monophosphate (cGMP) and asperlicin, indicating that activation of the Na+-H+ antiport caused by caerulein is mediated by CCK receptors. The effect of gastrin was dibutyryl cGMP and asperlicin insensitive, whereas the effect of pentagastrin was inhibited by the CCK antagonists but with a low affinity, indicating that the effect of gastrin and that of pentagastrin was CCK receptor independent. The calcium ionophore A23187 caused an increase in amiloride-sensitive 22Na uptake. However, the effect of caerulein, which increased internal calcium concentration, was not modified after depletion of intracellular calcium, and that of CCK-gastrin family peptides was not dependent on external calcium concentration. Activation of amiloride-sensitive 22Na uptake was also induced by 12-O-tetradecanoylphorbol 13-acetate and 1-oleoyl-2-acetyl-glycerol. Activation of protein kinase c may be involved in the mechanism of caerulein or gastrin in activating the Na+-H+ exchange.

A comparison of antigen-induced and calcium ionophore A23187 induced contraction of isolated guinea pig trachea

1981 ◽  
Vol 59 (10) ◽  
pp. 1031-1038 ◽  
Author(s):  
John F. Burka ◽  
Nigel A. M. Paterson
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
The Other ◽  
Ionophore A23187 ◽  
Lipoxygenase Inhibitor ◽  
Lipoxygenase Pathway ◽  
Histamine Secretion ◽  
Other Hand

Ovalbumin (OA) and the calcium ionophore A23187 induced a dose-dependent contraction of guinea pig tracheal strips. The OA-induced contraction (of sensitized trachea) consisted of an initial peak contraction, maximal between 5 and 10 min, followed by a very gradual decline from the peak. On the other hand, A23187 induced a sustained contraction of the trachea with a more gradual onset. Both antigen- and A23187-induced contractions required the presence of extracellular calcium. The response was not reduced by delaying (up to 10 min) the addition of calcium, suggesting that the mechanism of antigen-induced contraction differs from that of antigen-induced histamine secretion from rat mast cells and human basophils. The 1st min of the OA-induced contraction was inhibited significantly by mepyramine (10−5 M) suggesting that histamine contributed to the contraction at this time point. In contrast, A23187-induced contraction was unaffected by mepyramine. On the other hand, both the A23187-induced contraction and the prolonged phase of the OA-induced contraction were enhanced by indomethacin, a cyclooxygenase inhibitor, and inhibited by phenidone, a cyclooxygenase–lipoxygenase inhibitor. This suggests that a product of the lipoxygenase pathway of arachidonic acid metabolism contributes to OA- and A23187-induced contraction of the guinea pig trachea.

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