scholarly journals Acute α1-adrenergic stimulation of cardiac protein synthesis may involve increased intracellular pH and protein kinase activity

1991 ◽  
Vol 273 (2) ◽  
pp. 347-353 ◽  
Author(s):  
S J Fuller ◽  
C J Gaitanaki ◽  
R J Hatchett ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase ◽  
Intracellular Ph ◽  
Polynomial Regression ◽  
Kinase Inhibitor ◽  
Adenine Nucleotide ◽  
Protein Kinase Activity ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Stimulation Of

In the presence of 5 microM-DL-propranolol and in HCO3(-)-containing buffers, 1 microM-adrenaline acutely stimulated protein synthesis by about 25% in the anterogradely perfused rat heart. This stimulation was opposed by low (1-10 nM) concentrations of prazosin, but not by similar concentrations of yohimbine, suggesting involvement of the alpha 1-adrenoceptor. Under the same conditions, adrenaline raised intracellular pH (pHi) by about 0.1 unit. The increase in pHi induced by adrenaline was prevented by 5 nM-prazosin, but not by 5 nM-yohimbine, again suggesting involvement of the alpha 1-adrenoceptor. Since an increase in pHi stimulates protein synthesis in the heart [Sugden & Fuller (1991) Biochem. J. 273, 339-346], the increase in pHi induced by adrenaline may be involved in its stimulation of protein synthesis. Adrenaline also increased phosphocreatine concentrations. As discussed, the increase in pHi induced by adrenaline may be responsible for this effect. Using second-order polynomial regression analysis, we showed that rates of protein synthesis were significantly correlated (P less than 0.0001) with phosphocreatine concentrations. We discuss two possible reasons for this correlation: (i) increases in pHi stimulate protein synthesis and separately raise phosphocreatine concentrations, or (ii) the increase in protein synthesis rates is a consequence of the raised phosphocreatine concentrations induced by the increase in pHi. Rates of protein synthesis were not significantly correlated with ATP/ADP concentration ratios, nor with any of the following: ATP, ADP, AMP or total adenine nucleotide concentrations. In freshly isolated adult rat cardiomyocytes, the protein kinase inhibitor staurosporine (1 microM) prevented stimulation of protein synthesis by 0.3 microM-adrenaline (and by 1 microM-phorbol 12-myristate 13-acetate or 1 m-unit of insulin/ml). The results are discussed within a mechanistic framework initiated by stimulation of the hydrolysis of membrane phospholipids by alpha 1-adrenergic agonists.

β-Adrenergic stimulation of cyclic AMP and protein kinase activity in the thyroid

Nature ◽  
1975 ◽  
Vol 254 (5498) ◽  
pp. 347-349 ◽  
Author(s):  
STEPHEN W. SPAULDING ◽  
GERARD N. BURROW
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Adrenergic Stimulation ◽  
Stimulation Of

Phosphorylation-dependent modulation of cardiac calcium current by intracellular free magnesium

2001 ◽  
Vol 281 (4) ◽  
pp. H1532-H1544 ◽  
Author(s):  
Siegried Pelzer ◽  
Chicuong La ◽  
Dieter J. Pelzer
Keyword(s):  
Protein Kinase ◽  
Protein Phosphorylation ◽  
Calcium Current ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Protein Kinase Activity ◽  
Inhibitory Effects ◽  
Maximal Stimulation ◽  
Free Magnesium ◽  
Stimulation Of

We compared the effects of cytosolic free magnesium (Mg[Formula: see text]) on L-type Ca2+ current ( I Ca,L) in patch-clamped guinea pig ventricular cardiomyocytes under basal conditions, after inhibition of protein phosphorylation, and after stimulation of cAMP-mediated phosphorylation. Basal I Ca,L density displayed a bimodal dependence on the concentration of Mg[Formula: see text]([Mg2+]i; 10−6–10−2 M), which changed significantly as cell dialysis progressed due to a pronounced and long-lasting rundown of I Ca,L in low-Mg2+ dialysates. Ten minutes after patch breakthrough, I Ca,L density (at +10 mV) in Mg[Formula: see text]-depleted cells ([Mg2+]i∼1 μM) was elevated, increased to a maximum at ∼20 μM [Mg2+]i, and declined steeply at higher [Mg2+]i. Treatment with the broad-spectrum protein kinase inhibitor K252a (10 μM) reduced I Ca,L density and abolished these effects of Mg[Formula: see text] except for a negative shift of I Ca,L-voltage relations with increasing [Mg2+]i. Maximal stimulation of cAMP-mediated phosphorylation occluded the Mg[Formula: see text]-induced stimulation of I Ca,L and prevented inhibitory effects of the ion at [Mg2+]i <1 mM but not at higher concentrations. These results show that the modulation of I Ca,L by Mg[Formula: see text] requires protein kinase activity and likely originates from interactions of the ion with proteins involved in the regulation of protein phosphorylation/dephosphorylation. Stimulatory effects of Mg[Formula: see text] on I Ca,L seem to increase the cAMP-mediated phosphorylation of Ca2+ channels, whereas inhibitory effects of Mg[Formula: see text] appear to curtail and/or reverse cAMP-mediated phosphorylation.

cAMP and protein synthesis in isolated adult rat heart preparations

1993 ◽  
Vol 265 (5) ◽  
pp. C1247-C1257 ◽  
Author(s):  
M. A. Bogoyevitch ◽  
S. J. Fuller ◽  
P. H. Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase ◽  
Rat Heart ◽  
Adenine Nucleotide ◽  
Adrenergic Agonists ◽  
Perfused Heart ◽  
Dependent Protein Kinase ◽  
Adult Rat ◽  
Dependent Protein ◽  
Stimulation Of

The involvement of adenosine 3',5'-cyclic monophosphate (cAMP) in the stimulation of ventricular protein synthesis by aortic hypertension or adrenergic agonists in the adult rat heart was investigated. In either the retrogradely or anterogradely perfused heart, aortic hypertension increased protein synthesis rates by up to 19%. However, no changes in cAMP concentrations or in cAMP-dependent protein kinase activity ratios could be detected either at early (< 5 min) or late (90 min) time points. Although isoproterenol, 3-isobutyl-1-methylxanthine, or forskolin raised cAMP concentrations (by up to 4.5-fold) and cAMP-dependent protein kinase ratios (by up to 4-fold), protein synthesis rates were not increased; however, under some perfusion conditions, glucagon did stimulate protein synthesis by 25%. Epinephrine stimulated protein synthesis by up to 32%, an effect that was not prevented by propranolol. Phenylephrine also stimulated protein synthesis, an effect that was prevented by prazosin but was unaffected by yohimbine. These findings implicate the alpha 1-adrenoceptor in the regulation of cardiac protein synthesis. Because changes in adenine nucleotide concentrations were similar in hearts perfused with epinephrine or with the agents that raised cAMP, it is unlikely that adenine nucleotide depletion is responsible for the failure to observe effects of the latter group of agents on protein synthesis. Although isoproterenol or forskolin raised cAMP concentrations in isolated ventricular cardiomyocytes where ATP depletion was minimal, neither stimulated protein synthesis. alpha 1-Adrenergic agonists stimulate phosphoinositide hydrolysis in the heart (Brown, J. H., I. L. Buxton, and L. L. Brunton. Circ. Res. 57:532-537, 1985). Aortic hypertension doubled the rate of phosphoinositide hydrolysis in the perfused heart. We suggest that the phosphoinositide-linked signal transduction pathway is more likely to be involved in stimulation of cardiac protein synthesis by hypertension or adrenergic agonism than the adenylyl cyclase/cAMP-linked pathway.

Alpha 1-adrenergic stimulation of Na-H exchange in cardiac myocytes

1992 ◽  
Vol 263 (5) ◽  
pp. C1096-C1102 ◽  
Author(s):  
M. A. Wallert ◽  
O. Frohlich
Keyword(s):  
Protein Kinase C ◽  
Steady State ◽  
Protein Kinase ◽  
Intracellular Ph ◽  
Ph Dependence ◽  
Adrenergic Stimulation ◽  
Adult Rat ◽  
Kinase C ◽  
Rat Heart Myocytes ◽  
Stimulation Of

The activation of Na-H exchange in adult rat heart myocytes was characterized in response to a phorbol ester (phorbol 12-myristate 13-acetate) and an alpha 1-adrenergic agonist [6-fluoronorepinephrine (6F-NE)]. Transport activation was assessed by determining the initial rate with which intracellular pH (pHi) was returned from an acid pulse and by following changes in steady-state pHi; pHi was determined by a pH-sensitive fluorescent dye. Both agonists shifted the intracellular pH dependence of Na-H exchange by 0.10-0.15 pH units in the alkaline direction. This shift was prevented by the presence of sphingosine and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), inhibitors of protein kinase C. The agonists also alkalinized pHi at steady state. The alkalinization by 6F-NE was blocked by prazosin and H-7. This indicates that the adrenergic stimulation of cardiac Na-H exchange is mediated by an alpha 1-adrenergic mechanism and very likely involves the activation of protein kinase C.

Regulation of protein kinase by vasopressin in renal medulla in situ

1977 ◽  
Vol 232 (1) ◽  
pp. F50-F57
Author(s):  
T. P. Dousa ◽  
L. D. Barnes
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Renal Medulla ◽  
Protein Kinase Activity ◽  
Kinase Activation ◽  
Heat Stable ◽  
Protein Kinase Activation ◽  
Heat Stable Protein

Results of this study demonstrate that vasopressin activates protein kinase in intact renal medullary cells as detected by measurement of the (-cyclic AMP/+cyclic AMP) protein kinase activity ratios in freshly prepared tissue extracts (40,000 X g supernates) from bovine renal medullary slices. The activation of protein kinase was specific for vasopressin since parathyroid hormone, histamine, angiotensin II, or the inactive analog of vasopressin did not activate protein kinase. There was a direct correlation between the extent of protein kinase activation and the elevation in tissue levels of cyclic AMP elicited by increasing doses of vasopressin or with an increase in incubation time. The elevation of tissue cyclic AMP level and maximum activation of protein kinase reached maximum level at a vasopressin concentration of about 2 X 10(-9) M. Incubation of slices with vasopressin caused a dose-dependent decrease in the cyclic AMP-dependent protein kinase activity in the 40,000 X g supernate of homogenate from the renal medullary slices. This effect of vasopressin was specific for protein kinase since activity of lactate dehydrogenase or a specific [3H]colchicine-binding activity was not affected, and the decrease in the protein kinase was not due to the accumulation of a heat-stable protein kinase inhibitor. There was an increase in protein kinase was not due to the accumulation of a heat-stable protein kinase inhibitor. There was an increase in protein kinase activity extracted from 40,000 X g pellets of homogenate prepared from slices exposed to vasopressin. Results thus provide evidence that cyclic AMP-mediated protein kinase activation in the intact cells is an integral part of cellular response of the mammalian renal medulla to vasopressin.

scholarly journals Cytoplasmic [Ca2+] and intracellular pH in lymphocytes. Role of membrane potential and volume-activated Na+/H+ exchange.

1987 ◽  
Vol 89 (2) ◽  
pp. 185-213 ◽  
Author(s):  
S Grinstein ◽  
S Cohen
Keyword(s):  
Protein Kinase C ◽  
Membrane Potential ◽  
Protein Kinase ◽  
Intracellular Ph ◽  
Enzyme Treatment ◽  
Membrane Hyperpolarization ◽  
Kinase C ◽  
Free Media ◽  
Stimulation Of

The effect of elevating cytoplasmic Ca2+ [( Ca2+]i) on the intracellular pH (pHi) of thymic lymphocytes was investigated. In Na+-containing media, treatment of the cells with ionomycin, a divalent cation ionophore, induced a moderate cytoplasmic alkalinization. In the presence of amiloride or in Na+-free media, an acidification was observed. This acidification is at least partly due to H+ (equivalent) uptake in response to membrane hyperpolarization since: it was enhanced by pretreatment with conductive protonophores, it could be mimicked by valinomycin, and it was decreased by depolarization with K+ or gramicidin. In addition, activation of metabolic H+ production also contributes to the acidification. The alkalinization is due to Na+/H+ exchange inasmuch as it is Na+ dependent, amiloride sensitive, and accompanied by H+ efflux and net Na+ gain. A shift in the pHi dependence underlies the activation of the antiport. The effect of [Ca2+]i on Na+/H+ exchange was not associated with redistribution of protein kinase C and was also observed in cells previously depleted of this enzyme. Treatment with ionomycin induced significant cell shrinking. Prevention of shrinking largely eliminated the activation of the antiport. Moreover, a comparable shrinking produced by hypertonic media also activated the antiport. It is concluded that stimulation of Na+/H+ exchange by elevation of [Ca2+]i is due, at least in part, to cell shrinking and does not require stimulation of protein kinase C.

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