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Home / Equine Research Bank / Br J Pharmacol / (+)-[3H]-PN 200-110 binding to cell membranes and intact str...
British journal of pharmacology1989; 97(1); 256-262; doi: 10.1111/j.1476-5381.1989.tb11949.x

(+)-[3H]-PN 200-110 binding to cell membranes and intact strips of portal vein smooth muscle: characterization and modulation by membrane potential and divalent cations.

Abstract: 1. Specific binding of the calcium-antagonist dihydropyridine derivative, (+)-[3H]-PN 200-110 (isradipine), to cell membranes of equine portal vein smooth muscle was compared with binding to intact strips isolated from rat portal veins. 2. Specific binding to vascular smooth muscle membranes was of high affinity, saturable and reversible. The dissociation constant obtained from association and dissociation kinetics of (+)-[3H]-PN 200-110 was similar to that obtained from equilibrium binding and competition experiments. 3. Specific binding of (+)-[3H]-PN 200-110 was completely displaced by unlabelled dihydropyridines. Among other calcium antagonists, D888 and (+)-cis-diltiazem partially inhibited the binding at 25 degrees C. At 37 degrees C, only (+)-cis-diltiazem stimulated the binding. LaCl3, CdCl2, NiCl2, CoCl2 had inhibitory effects, whereas KCl and NaCl had no effect. 4. When intact strips of portal vein were incubated in high external potassium concentrations for 30 min, the Kd was lowered to 0.04 +/- 0.01 nM from the control value of 0.14 +/- 0.02 nM (n = 5), thereby indicating that (+)-[3H]-PN 200-110 bound to voltage-dependent calcium channels, with a higher affinity, in the depolarized state. 5. When external Ca2+ was removed or substituted with Ba2+ or Sr2+, Kd values increased suggesting that the dihydropyridine binding to intact strips was modulated by binding of Ca2+ ions to voltage-dependent calcium channels.
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Publication Date: 1989-05-01 PubMed ID: 2524235PubMed Central: PMC1854475DOI: 10.1111/j.1476-5381.1989.tb11949.xGoogle Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study analyzed the specific binding of the calcium-antagonist dihydropyridine derivative, (+)-[3H]-PN 200-110 (also known as isradipine), to cell membranes of equine portal vein smooth muscle. The research found that this binding is of high affinity, saturable, and reversible. The binding was influenced by a change in temperature and the presence of different cations.

Objective and Methods

  • The study aimed to understand the characteristics of dihydropyridine derivative (+)-[3H]-PN 200-110 binding to the smooth muscle cell membranes constituted of static strips isolated from rat portal veins.
  • The researchers compared specific binding of (+)-[3H]-PN 200-110 to vascular smooth muscle membranes. They analyzed the dissociation constant obtained from association and dissociation kinetics of (+)-[3H]-PN 200-110 and data from equilibrium binding and competition experiments.

Results

  • The researchers found that the specific binding of (+)-[3H]-PN 200-110 to vascular smooth muscle membranes was of high affinity. Meaning, the molecules showed a significant tendency to combine with each other. It was also found to be saturable and reversible.
  • Unlabeled dihydropyridines completely displaced the specific binding of (+)-[3H]-PN 200-110. Other calcium antagonists like D888 and (+)-cis-diltiazem partially inhibited the binding at a temperature of 25 degrees Celsius. Surprisingly, at 37 degrees Celsius, only (+)-cis-diltiazem stimulated the binding.
  • Various salts such as LaCl3, CdCl2, NiCl2, and CoCl2 were also found to have inhibitory effects on binding, while KCl and NaCl did not affect it.

Membrane Potential and Divalent Cations Effects

  • The researchers incubated intact strips of portal vein in high external potassium concentrations for 30 minutes to examine the effect of membrane potential. Following this incubation, the dissociation constant (Kd) dropped from the control value of 0.14 +/- 0.02 nM to 0.04 +/- 0.01 nM, indicating that (+)-[3H]-PN 200-110 bound with higher affinity to voltage-dependent calcium channels in the depolarized state.
  • When external calcium (Ca2+) was removed or replaced with barium (Ba2+) or strontium (Sr2+), Kd values increased. This suggested that the dihydropyridine binding to intact strips was affected by the binding of calcium ions to voltage-dependent calcium channels.

Cite This Article

APA
Dacquet C, Loirand G, Rakotoarisoa L, Mironneau C, Mironneau J. (1989). (+)-[3H]-PN 200-110 binding to cell membranes and intact strips of portal vein smooth muscle: characterization and modulation by membrane potential and divalent cations. Br J Pharmacol, 97(1), 256-262. https://doi.org/10.1111/j.1476-5381.1989.tb11949.x

Publication

British journal of pharmacology
ISSN: 0007-1188
NlmUniqueID: 7502536
Country: England
Language: English
Volume: 97
Issue: 1
Pages: 256-262

Researcher Affiliations

Dacquet, C
  • Laboratorie de Physiologie Cellulaire et Pharmacologie, Moléculaire, INSERM JF 88.13, Université de Bordeaux II, France.
Loirand, G
    Rakotoarisoa, L
      Mironneau, C
        Mironneau, J

          MeSH Terms

          • Animals
          • Calcium Channel Blockers / metabolism
          • Cations / pharmacology
          • Cell Membrane / drug effects
          • Cell Membrane / metabolism
          • Horses
          • In Vitro Techniques
          • Isradipine
          • Membrane Potentials / drug effects
          • Muscle, Smooth, Vascular / drug effects
          • Muscle, Smooth, Vascular / metabolism
          • Oxadiazoles / metabolism
          • Portal Vein / drug effects
          • Portal Vein / metabolism
          • Rats

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          Citations

          This article has been cited 5 times.
          1. Krautwurst D, Scherübl H, Kleppisch T, Hescheler J, Schultz G. Dihydropyridine binding and Ca(2+)-channel characterization in clonal calcitonin-secreting cells. Biochem J 1993 Feb 1;289 ( Pt 3)(Pt 3):659-65.
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          2. Martin C, Dacquet C, Mironneau C, Mironneau J. Caffeine-induced inhibition of calcium channel current in cultured smooth cells from pregnant rat myometrium. Br J Pharmacol 1989 Oct;98(2):493-8.
            doi: 10.1111/j.1476-5381.1989.tb12622.xpubmed: 2555010google scholar: lookup
          3. Mironneau J, Sayet I, Rakotoarisoa L, Dacquet C, Mironneau C. Interactions of spironolactone with (+)-[3H]-isradipine and (-)-[3H]-desmethoxyverapamil binding sites in vascular smooth muscle. Br J Pharmacol 1990 Sep;101(1):6-7.
            doi: 10.1111/j.1476-5381.1990.tb12077.xpubmed: 2149292google scholar: lookup
          4. Treherne JM, Stern JS, Flack WJ, Young JM. Inhibition by cations of antagonist binding to histamine H1-receptors: differential effect of sodium ions on the binding of two radioligands. Br J Pharmacol 1991 Jul;103(3):1745-51.
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          5. Mironneau J, Yamamoto T, Sayet I, Arnaudeau S, Rakotoarisoa L, Mironneau C. Effect of dihydropyridines on calcium channels in isolated smooth muscle cells from rat vena cava. Br J Pharmacol 1992 Feb;105(2):321-8.
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