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Shelly DA, He S, Moseley A, Weber C, Stegemeyer M, Lynch RM, Lingrel J, Paul RJ. Na(+) pump alpha 2-isoform specifically couples to contractility in vascular smooth muscle: evidence from gene-targeted neonatal mice. Am J Physiol Cell Physiol 2003; 286:C813-20. [PMID: 14627611 DOI: 10.1152/ajpcell.00389.2003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The relative expression of alpha(1)- and alpha(2)-Na(+)/K(+)-ATPase isoforms found in vascular smooth muscle is developmentally regulated and under hormonal and neurogenic control. The physiological roles of these isoforms in vascular function are not known. It has been postulated that the alpha(1)-isoform serves a "housekeeping" role, whereas the alpha(2)-isoform localizes to a subsarcolemmal compartment and modulates contractility. To test this hypothesis, isoform-specific gene-targeted mice in which the mRNA for either the alpha(1)- or the alpha(2)-Na(+)/K(+)-ATPase isoform was ablated were utilized. Both of these knockouts, alpha(1)(-/-) and alpha(2)(-/-), are lethal; the latter dies at birth, which allows this neonatal aorta to be studied. Isometric force in alpha(2)(-/-)-aorta was more sensitive to contractile agonists and less sensitive to the vasodilators forskolin and sodium nitroprusside (SNP) than wild-type (WT) aorta; alpha(2)(+/-)-aortas had intermediate values. In contrast, neonatal alpha(1)(+/-)-aorta was similar to WT. Western blot analysis indicated a population of 70% alpha(1)- and 30% alpha(2)-isoforms in the WT. Thus in terms of the total Na(+)/K(+)-ATPase protein, the alpha(2)(-/-)-aorta (at 70%) would be similar to the alpha(1)(+/-)-aorta (at 65%) but with a dramatically different phenotype. These data suggest that individual alpha-isoforms of the Na(+)/K(+)-ATPase differ functionally and that the alpha(2)-isoform couples more strongly to activation-relaxation pathways. Three-dimensional image-acquisition and deconvolution analyses suggest that the alpha(2)-isoform is distributed differently than the alpha(1)-isoform. Importantly, these isoforms do not localize to the same regions.
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Affiliation(s)
- Daniel A Shelly
- Departments of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0576, USA
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Gusev GP, Agalakova NI. Activation of the Na,K-pump by isoproterenol, methylxanthines, and iodoacetate in erythrocytes of the frogRana temporaria. J EVOL BIOCHEM PHYS+ 2000. [DOI: 10.1007/bf02754327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Gusev GP, Agalakova NI, Lapin AV. Activation of the Na(+)-K+ pump in frog erythrocytes by catecholamines and phosphodiesterase blockers. Biochem Pharmacol 1996; 52:1347-53. [PMID: 8937444 DOI: 10.1016/s0006-2952(96)00412-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
K+ and Na+ influx into frog erythrocytes incubated in standard saline was studied using 86Rb and 22Na as tracers. 10 microM isoproterenol (ISP) produced a significant increase in K+ influx for the first 15 min, which was sustained during the entire 60 min of cell incubation. Treatment of red cells with the phosphodiesterase (PDE) blockers theophylline (THEO, 1 and 5 mM) or 3-isobutyl-1-methylxanthine (IBMX, 0.5 mM) was also accompanied by an enhancement in K+ influx. A distinct additive effect on K+ influx into red cells was found when ISP and THEO or IBMX were added together. The increase in K+ transport induced by ISP plus IBMX was totally abolished by pretreatment of red cells with 0.1 mM ouabain. The ouabain-sensitive K+ influx in frog erythrocytes was elevated in the presence of ISP plus IBMX to 2.05 +/- 0.45, as compared with the control level of 0.39 +/- 0.11 mmol/L cells/hr (P < 0.001). Similar effects of ISP and IBMX on K+ influx were observed after chloride was replaced by nitrate. A dose-related increase in K+ influx into frog erythrocytes was observed at ISP concentrations of 10(-8)-10(-6) M, with a half-maximal stimulatory concentration of approximately 0.02 microM. The effects of ISP (10(-8)-10(-5) M) on K+ transport were completely abolished with 10 microM of the beta-adrenergic blocker propranolol, but alpha-adrenergic antagonists (phentolamine, prazosin, and yohimbine) did not alter the ISP-induced increase in K+ influx. The drugs tested had no effect on 22Na influx in frog red cells, but ISP produced a small decline (13%) in intracellular Na+ concentration. Thus, our study indicates that catecholamines and PDE blockers enhance K+ (86Rb) transport in frog erythrocytes mediated by Na(+)-K+ pump activity. The frog erythrocyte membrane may serve as a convenient model to investigate the hormonal modulation of the Na(+)-K+.
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Affiliation(s)
- G P Gusev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St-Petersburg, Russia.
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Fay FS, Yagi S, Iloh T, McCarron J, McGeown G, Walsh J, lkebe M, Moore ED. Cellular and molecular physiology of calcium signalling in smooth muscle cells. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0021-5198(19)59891-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Moore ED, Fogarty KE, Fay FS. Role of Na(+)-Ca2+ exchanger in beta-adrenergic relaxation of single smooth muscle cells. Ann N Y Acad Sci 1991; 639:543-9. [PMID: 1664707 DOI: 10.1111/j.1749-6632.1991.tb17347.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- E D Moore
- Department of Physiology/Biomedical Imaging Group, University of Massachusetts Medical Center, Worcester 01605
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Giembycz MA, Raeburn D. Putative substrates for cyclic nucleotide-dependent protein kinases and the control of airway smooth muscle tone. JOURNAL OF AUTONOMIC PHARMACOLOGY 1991; 11:365-98. [PMID: 1662219 DOI: 10.1111/j.1474-8673.1991.tb00260.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M A Giembycz
- Department of Thoracic Medicine, National Heart and Lung Institute, Royal Brompton and National Heart and Lung Hospital, London, UK
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Skajaa K, Everts ME, Clausen T, Forman A. Effects of magnesium and terbutaline on contractility and K+ uptake in isolated human uterine muscle. Am J Obstet Gynecol 1991; 165:1543-51. [PMID: 1659786 DOI: 10.1016/0002-9378(91)90403-e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mg++ (3 and 6 mmol/L), the beta 2-adrenergic agonist terbutaline (1 and 10 mumol/L), and dibutyryl cyclic adenosine 5'-monophosphate (0.1 and 1 mmol/L) suppressed spontaneous activity and the increase in contractile activity induced by ouabain or K(+)-free buffer in isolated human pregnant myometrium. The ouabain-suppressible rubidium 86 or potassium 42 uptake was unaffected by the presence of Mg++ (3 and 6 mmol/L), the beta 2-adrenergic agonist terbutaline (1 and 10 mumol/L), or dibutyryl cyclic adenosine 5'-monophosphate (1 mmol/L). However, loading of the strips with Na+ and incubation in high K+ induced a fivefold increase in rubidium 86 uptake. On the basis of these flux rates, our previous data on the total concentration of sodium-potassium pumps in the human myometrium, and an estimated maximum transport rate of the sodium-potassium pump of 8900 K+ ions per minute at 30 degrees C, it could be calculated that the sodium-potassium pump in the Na(+)-loaded strips reached around 80% of its maximal rate. Taken together, these results showed that the relaxant effects of Mg++, terbutaline, and dibutyryl cyclic adenosine 5'-monophosphate on human myometrium are not due to a stimulation of active sodium-potassium transport.
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Affiliation(s)
- K Skajaa
- Department of Obstetrics and Gynecology, University of Aarhus, Denmark
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8
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Effects of magnesium and terbutaline on contractility and K+ uptake in isolated human uterine muscle. Am J Obstet Gynecol 1991. [DOI: 10.1016/s0002-9378(12)90797-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gleason MM, Medow MS, Tulenko TN. Excess membrane cholesterol alters calcium movements, cytosolic calcium levels, and membrane fluidity in arterial smooth muscle cells. Circ Res 1991; 69:216-27. [PMID: 2054935 DOI: 10.1161/01.res.69.1.216] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The relations between membrane cholesterol content, basal (unstimulated) transmembrane 45Ca2+ movements, cytosolic calcium levels, and membrane fluidity were investigated in cultured rabbit aortic smooth muscle cells (SMCs) and isolated SMC plasma membrane microsomes. SMCs were enriched with unesterified (free) cholesterol (FC) for 18-24 hours with medium containing human low density lipoprotein and FC-rich phospholipid (PL) liposomes. This procedure increased cholesterol mass without affecting PL mass, resulting in an increase in the FC/PL molar ratio compared with controls in cells (67% FC increase, p less than 0.001; 43% FC/PL ratio increase, p less than 0.01) and in SMC microsomes (52% FC increase, p less than 0.05; 43% FC/PL ratio increase, p less than 0.05). Cholesterol enrichment also increased unstimulated 45Ca2+ influx (p less than 0.001) and efflux (p less than 0.05). Cellular cholesterol content correlated in a linear fashion with these changes (influx: r = 0.722, p less than 0.01; efflux: r = 0.951, p less than 0.05). In addition, cytosolic calcium levels increased approximately 34% (p less than 0.01) with cholesterol enrichment. The cholesterol-induced increase in 45Ca2+ influx was reversible with time and demonstrated sensitivity to the channel blockers. Fluorescence anisotropy measured from 5 degrees C to 40 degrees C using the fluorophore diphenylhexatriene showed decreased membrane fluidity in microsomal membranes obtained from cholesterol-enriched SMCs compared with controls (p less than 0.02). These results suggest that the SMC plasma membrane is very sensitive to cholesterol enrichment with liposomes or human low density lipoprotein and that increases in membrane cholesterol content increase cytosolic calcium levels in SMCs, are associated with a decrease in membrane fluidity, and unmask a new, or otherwise silent, dihydropyridine-sensitive calcium channel that may be involved in altered arterial wall properties with serum hypercholesterolemia.
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Affiliation(s)
- M M Gleason
- Department of Physiology and Biochemistry, Medical College of Pennsylvania, Philadelphia 19129
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Bolton TB. Electrophysiology of the intestinal musculature. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Daniel EE, Collins SM, Fox JET, Huizinga JD. Pharmacology of drugs acting on gastrointestinal motility. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Sanborn BM. Rat myometrial Na/K ATPase is increased by serum but not by isoproterenol and relaxin. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1989; 93:341-4. [PMID: 2572389 DOI: 10.1016/0742-8413(89)90244-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Na/K ATPase activity in rat myometrial cells in culture exhibited a Kapp of 0.93 mM for Rb+ and a Ki of 31 microM for ouabain with respect to Rb+. 2. 86Rb+ uptake was stimulated by serum and monensin but was not affected by the uterine relaxants isoproterenol and relaxin in 0.5-7.5 mM Rb+. Nonetheless, these relaxants elicited significant increases in 45Ca2+ efflux under similar conditions. 3. These data suggest that increased Na/Ca exchange resulting from a stimulation of Na/K ATPase is not involved in the mechanism of action of relaxin and isoproterenol in the uterus.
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Affiliation(s)
- B M Sanborn
- Department of Biochemistry and Molecular Biology, University of Texas Medical-School, Houston 77030
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Stoclet JC, Boulanger-Saunier C, Lassegue B, Lugnier C. Cyclic nucleotides and calcium regulation in heart and smooth muscle cells. Ann N Y Acad Sci 1988; 522:106-15. [PMID: 2837121 DOI: 10.1111/j.1749-6632.1988.tb33348.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- J C Stoclet
- UA CNRS 600, Faculty of Pharmacy, Louis Pasteur University, Strasbourg, France
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Silver PJ. Pharmacological modulation of phosphorylation mechanisms in heart and vasculature. Drug Dev Res 1988. [DOI: 10.1002/ddr.430120204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Fay FS, Williams DA, Kargacin G, Tucker RW, Scanlon M. Role of local [Ca+2] in the control of cell function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 232:213-9. [PMID: 3063079 DOI: 10.1007/978-1-4757-0007-7_23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- F S Fay
- Dept. of Physiology, University of Massachusetts Medical School, Worcester 01655
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Ousterhout JM, Sperelakis N. Cyclic nucleotides depress action potentials in cultured aortic smooth muscle cells. Eur J Pharmacol 1987; 144:7-14. [PMID: 2830120 DOI: 10.1016/0014-2999(87)90003-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of cyclic nucleotide analogs and related agents on the Ca2+ dependent action potentials of cultured rat aortic smooth muscle cells (reaggregates) were examined. The action potentials were elicited by electrical stimulation in the presence of tetraethylammonium (TEA, 5-15 mM). Superfusion of the aortic cells with analogs of cyclic AMP (dibutyryl or 8-bromo-cyclic AMP, 1 mM), isoproterenol (1-10 microM) and forskolin (1-10 microM) depressed and abolished the TEA-induced action potentials. Abolition of the action potentials by these agents was reversible and was accompanied by some hyperpolarization of the membrane. Superfusion with 8-bromo-cyclic GMP (0.1-1 mM) also depressed or abolished the TEA-induced action potentials, whereas dibutyryl cyclic GMP (1 mM) and sodium nitroprusside (10 microM) had little effect. Synthetic atrial natriuretic factor (0.01-0.1 microM) had inhibitory effects in most experiments. Thus, depression of membrane excitability may be a contributing factor in the relaxation of aortic smooth muscle produced by some agents that increase intracellular levels of cyclic nucleotides.
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Affiliation(s)
- J M Ousterhout
- Department of Physiology and Biophysics, University of Cincinnati, College of Medicine, Ohio 45267-0576
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Giembycz MA, Rodger IW. Electrophysiological and other aspects of excitation-contraction coupling and uncoupling in mammalian airway smooth muscle. Life Sci 1987; 41:111-32. [PMID: 2439865 DOI: 10.1016/0024-3205(87)90485-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this article the electrophysiological events which are believed to underly agonist-induced contraction and relaxation of airway smooth muscle are reviewed, with special emphasis on the indispensable role of the Ca ion. The contribution made by Na, K, Ca and Cl to, and the role that the electrogenic Na:K-dependent ATPase plays in, the maintenance of the resting membrane potential in both normal and sensitised airway smooth muscle cells is described together with the permeability changes that occur in the plasmalemma in response to excitatory and inhibitory agonists. In addition, the currently available evidence for the existence of potential-sensitive and receptor-operated Ca channels in respiratory smooth muscle, and how such channels may be involved in the regulation of airway calibre, is critically assessed.
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Abstract
The beta-action of catecholamines on lymphatic smooth muscle was studied by observing the effect of isoprenaline on electrical and mechanical activity in the double sucrose-gap. Action potentials and phasic contractions evoked by depolarizing pulses were abolished within 2 min of drug addition. Isoprenaline hyperpolarized the membrane and increased membrane conductance. Tetraethylammonium (10 mM) did not itself affect membrane resistance but reduced the hyperpolarization and the increase in conductance caused by isoprenaline. Removal of K+ from the external solution reduced membrane conductance and increased the hyperpolarization due to isoprenaline. When the NaCl content of Krebs solution was replaced with LiCl or choline chloride, isoprenaline no longer blocked action potential firing and its effects on phasic contractions and membrane conductance were reduced. In contrast, ouabain (10(-5) M) did not block the effect of isoprenaline on membrane potential and membrane conductance. These results suggest that beta-adrenergic inhibition of lymphatic smooth muscle involves an increase in an outward K+ current, though an additional metabolic effect cannot be ruled out.
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Lewis AJ, Musser JH, Chang J, Silver PJ. New approaches to bronchodilator and antiallergic drug therapy. PROGRESS IN MEDICINAL CHEMISTRY 1985; 22:293-359. [PMID: 3014605 DOI: 10.1016/s0079-6468(08)70234-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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