Contribution of ATP-Mediated Positive Feedback to Sympathetic Nerve-Induced Positive Inotropy in Guinea Pig Ventricular Myocardium

Biol Pharm Bull. 2021;44(3):458-460. doi: 10.1248/bpb.b20-00732.

Abstract

The functional role of ATP released from sympathetic nerve terminals was examined in isolated guinea pig ventricular papillary muscles. The contractile force of papillary muscles was increased by field electrical stimulation of sympathetic nerve endings. This increase was attenuated by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) or suramin, blockers of the P2X receptor, and was abolished by propranolol and prazosin. PPADS, suramin, and ATP affected neither the basal contractile force nor the positive inotropic effect of noradrenaline. These results provide functional evidence that ATP released from sympathetic nerve terminals enhances noradrenaline release and contributes to sympathetic nerve-induced inotropy.

Keywords: ATP; guinea-pig; noradrenaline release; sympathetic nerve; ventricle.

MeSH terms

  • Adenosine Diphosphate / analogs & derivatives
  • Adenosine Diphosphate / pharmacology
  • Adenosine Triphosphate / physiology*
  • Animals
  • Feedback, Physiological*
  • Guinea Pigs
  • Heart Ventricles
  • Male
  • Muscle Contraction
  • Norepinephrine / physiology
  • Papillary Muscles / physiology*
  • Prazosin / pharmacology
  • Propranolol / pharmacology
  • Pyridoxal Phosphate / analogs & derivatives
  • Pyridoxal Phosphate / pharmacology
  • Suramin / pharmacology
  • Sympathetic Nervous System*
  • Ventricular Function*

Substances

  • N(6)-methyl-2'-deoxyadenosine 3',5'-diphosphate
  • pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid
  • Pyridoxal Phosphate
  • Suramin
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • Propranolol
  • Norepinephrine
  • Prazosin