RT Journal Article
SR Electronic
T1 Effects of adrenochrome on calcium accumulating and adenosine triphosphatase activities of the rat heart microsomes.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 688
OP 693
VO 214
IS 3
A1 S Takeo
A1 G M Taam
A1 R E Beamish
A1 N S Dhalla
YR 1980
UL http://jpet.aspetjournals.org/content/214/3/688.abstract
AB The influence of adrenochrome (1-100 microgram/ml or 5.6 x 10(-6)-5.4 x 10(-4) M) on microsomal calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent adenosine triphosphatase (ATPase) activities was studied in vitro. Adrenochrome decreased microsomal calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent ATPase activities. The inhibitory effect of adrenochrome on microsomal calcium uptake activity of the isolated membrane was independent of pH (6.0-8.0), calcium concentrations (10-200 muM), protein concentration (0.02-0.10 mg/ml), temperature (25-37 degrees C) and incubation time (2-30 min). Kinetic study of calcium uptake activity in different concentrations of ATP showed that the inhibition was of a mixed type. Perfusion of hearts with adrenochrome resulted in marked depression in contractile force and the microsomal fraction obtained from these hearts showed depressed calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent ATPase activities. The depression in microsomal The influence of adrenochrome (1-100 microgram/ml or 5.6 x 10(-6)-an irreversible nature. It is proposed that cardiodepressant action of adrenochrome may partly be explained on the basis of its inhibitory effect on the calcium transporting ability of the sarcoplasmic reticulum.