scholarly journals Cyclic AMP-evoked oscillations of intracellular [Ca2+] in guinea-pig hepatocytes

1991 ◽  
Vol 275 (1) ◽  
pp. 277-280 ◽  
Author(s):  
T Capiod ◽  
J Noel ◽  
L Combettes ◽  
M Claret
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Intracellular Perfusion ◽  
Beta Adrenoceptor ◽  
Adrenoceptor Agonist ◽  
Patch Pipette

The effects of the beta-adrenoceptor agonist isoprenaline and cyclic AMP (cAMP) on cytosolic free Ca2+ ([Ca2+]i) were studied in the single guinea-pig hepatocyte. In common with InsP3-dependent agonists such as noradrenaline or angiotensin II, isoprenaline (0.5-10 microM) and cAMP (50-100 mM, perfused into the cell via the patch-pipette), were able to generate fast and slow fluctuations of [Ca2+]i. Responses to isoprenaline and cAMP also were observed in the absence of external Ca2+. Isoprenaline-evoked [Ca2+]i rises were not blocked by the intracellular perfusion of heparin, suggesting that these fluctuations are independent of the binding of InsP3 to its receptor.

Inhibitory potency of isoprenaline on guinea-pig and gravid human myometrium following extraneuronal uptake blockade

1995 ◽  
Vol 7 (1) ◽  
pp. 59
Author(s):  
M Kousides ◽  
ME Story ◽  
JN Pennefather ◽  
SP Ziccone ◽  
AW Ross
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Human Myometrium ◽  
Inhibitory Effects ◽  
Beta Adrenoceptor ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists ◽  
Myometrial Contractility ◽  
Beta Adrenoceptor Agonists ◽  
Evoked Contractions

The hypothesis that inhibitory effects of isoprenaline on myometrial contractility may be constrained by activation of putative intracellular beta-adrenoceptors negatively-coupled to adenylate cyclase was examined. Field-stimulated preparations of guinea-pig and human myometrium were used to examine the influence of the catecholamine extraneuronal uptake2 inhibitors, corticosterone and beta-oestradiol, on the inhibitory effects of the beta-adrenoceptor agonist, isoprenaline, on uterine contraction. Longitudinal and circular myometrial layers were obtained from guinea-pigs in dioestrus, primed with oestrogen before progesterone, or pregnant (Days 62-65). In the guinea-pig myometrium, corticosterone (30 microM) did not affect responses to isoprenaline. beta-oestradiol (10 microM) induced a small potentiation of the effects of isoprenaline on longitudinal myometrium from dioestrus guinea-pigs. Myometrial preparations were obtained from pregnant women (36-40 weeks gestation) undergoing caesarean section. Isoprenaline inhibited stimulation-evoked contractions in 7 of 10 preparations of the inner myometrial layer and in 5 of 8 preparations of outer myometrial layer. Corticosterone (30 microM) reduced the effects of isoprenaline on the inner layer and did not affect the outer layer. These results do not support the existence of mechanism involving isoprenaline-sensitive intracellular receptors which constrain responses to beta-adrenoceptor agonists.

Isoproterenol-induced thirst: renal and extrarenal mechanisms

1981 ◽  
Vol 241 (3) ◽  
pp. R152-R157 ◽  
Author(s):  
R. Rettig ◽  
D. Ganten ◽  
A. K. Johnson
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Water Intake ◽  
Related Factor ◽  
Beta Adrenoceptor ◽  
Arterial Baroreceptors ◽  
Arterial Blood ◽  
Adrenoceptor Agonist ◽  
Series Of Experiments ◽  
Pressure Changes

When given systemically, isoproterenol will induce water intake in various species. The drug also causes hypotension and renin release from the kidney. Angiotensin II and arterial baroreceptors have been hypothesized to be involved in the mediation of beta-adrenoceptor agonist-induced thirst, but their relative importance has been disputed. In the present series of experiments, isoproterenol was infused intravenously at different rates into nephrectomized and ureteric-ligated rats. Thus, different levels of hypotension could be achieved and maintained while water intake was measured. Also, plasma levels of angiotensin II were determined in ureteric-ligated rats following the intravenous infusion of a dipsogenic dose of isoproterenol. The results indicate that for moderate blood pressure changes a renal-related factor, probably angiotensin II, plays a major role in the mediation of isoproterenol-induced thirst. Under extreme conditions involving a very dramatic drop of arterial blood pressure, extrarenal mechanisms (e.g., arterial baroreceptors) are implicated.

Immunochemical visualization of cyclic AMP in myenteric neurons of guinea-pig small intestine+

2001 ◽  
Vol 120 (5) ◽  
pp. A683-A683
Author(s):  
J GUZMAN ◽  
S SHARP ◽  
J YU ◽  
F MCMORRIS ◽  
A WIEMELT ◽  
...  
Keyword(s):  
Small Intestine ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Myenteric Neurons
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