Responses of contractile function to ruthenium red in rat heart.

Isolated rat hearts exhibited a biphasic contractile response to varying concentrations of ruthenium red. A negative inotropic effect was observed with concentrations of 0.025-0.5 microM, whereas a reversal of these initial changes toward control or even exceeding the predrug values was obtained as ruthenium red concentration was increased to 2.5 or 5.0 microM. High concentrations (12.5-25.0 microM) of ruthenium red caused a sustained contracture. In contrast, isolated frog hearts exhibited only a sustained negative inotropic effect at 0.25-12.5 microM ruthenium red. In studies with rat heart, both negative and positive inotropic effects of 2.5 microM ruthenium red were blocked either by increasing the concentration of Ca2+ (from 1.25 to 5.0 mM) or by decreasing the concentration of Na+ (from 140 to 35 mM) in the perfusion medium. The contracture induced by 12.5 microM ruthenium red was markedly inhibited when Ca2+ in the medium was lowered. The positive inotropic effect and contracture due to ruthenium red were also blocked by 1 microM of verapamil and 1.5 mM of amiloride; however, these interventions did not prevent the initial negative inotropic effect of ruthenium red. These experiments suggest the role of extracellular Ca2+ in the dose- and time-dependent effects of ruthenium red on contractile function of the rat heart. Furthermore, the positive inotropic response to ruthenium red may be related to its actions on the Na+-dependent Ca2+ movements in the cardiac cell.
AuthorsM P Gupta, I R Innes, N S Dhalla
JournalThe American journal of physiology (Am J Physiol) Vol. 255 Issue 6 Pt 2 Pg. H1413-20 (Dec 1988) ISSN: 0002-9513 [Print] UNITED STATES
PMID2462366 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Ruthenium Red
  • Amiloride
  • Ruthenium
  • Sodium
  • Verapamil
  • Isoproterenol
  • Calcium
  • Amiloride (pharmacology)
  • Animals
  • Calcium (pharmacology)
  • In Vitro Techniques
  • Isoproterenol (pharmacology)
  • Male
  • Myocardial Contraction (drug effects)
  • Perfusion
  • Rats
  • Rats, Inbred Strains
  • Reference Values
  • Ruthenium (pharmacology)
  • Ruthenium Red (pharmacology)
  • Sodium (pharmacology)
  • Verapamil (pharmacology)

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research network!

Choose Username:
Verify Password: