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Selective cannabinoid receptor agonist HU-210 decreases pump function of isolated perfused heart: role of cAMP and

L N Maslov1, O V Lasukova, A V Krylatov

  • 1Aberdeen University, Great Britain. maslov@cardio.tsu.ru

Bulletin of Experimental Biology and Medicine
|September 2, 2005
PubMed

Insights

Cannabinoid receptor agonist HU-210 negatively impacts heart contractions and blocks isoproterenol effects. This occurs independently of changes in myocardial cyclic AMP levels, suggesting a different mechanism.

Area of Science:

  • Cardiovascular Pharmacology
  • Cannabinoid Receptor Research
  • Myocardial Function

Background:

  • Cannabinoid receptors are present in the heart, but their precise role in regulating myocardial contractility is not fully understood.
  • Beta-adrenoceptor agonists like isoproterenol typically increase heart rate and contractility via cAMP signaling.
  • Selective cannabinoid receptor agonists may influence cardiac function through various signaling pathways.

Purpose of the Study:

  • To investigate the effects of the selective cannabinoid receptor agonist HU-210 on rat myocardium contractility.
  • To determine the role of cyclic AMP (cAMP) and cyclic GMP (cGMP) in mediating HU-210's cardiac effects.
  • To assess whether HU-210 interferes with the inotropic and chronotropic actions of beta-adrenoceptor stimulation.

Main Methods:

  • Perfusion of isolated rat myocardium with Krebs-Henseleit solution.
  • Administration of the cannabinoid receptor agonist HU-210 (10 nM).
  • Measurement of heart contraction rate and strength, and intracellular cAMP and cGMP concentrations.
  • Assessment of HU-210's interaction with the effects of isoproterenol, a beta-adrenoceptor agonist.

Main Results:

  • HU-210 significantly decreased the rate and strength of heart contractions.
  • HU-210 completely blocked the positive inotropic and chronotropic effects of isoproterenol.
  • HU-210 reduced basal myocardial cAMP levels and abolished the isoproterenol-induced increase in cAMP; cGMP levels remained unchanged.
  • The observed negative inotropic and chronotropic effects of HU-210 did not correlate with decreased cAMP concentrations.

Conclusions:

  • The negative inotropic and chronotropic effects of HU-210 on rat myocardium are not mediated by a reduction in cAMP concentration.
  • Cannabinoid receptor activation by HU-210 interferes with beta-adrenoceptor signaling pathways in the heart.
  • Further research is needed to elucidate the specific signaling mechanisms underlying HU-210's cardiac effects.

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