Effect of amrinone in the working rat heart: influence of ischaemic damage, adenosine and calcium.
The action of amrinone on the isolated working rat heart was studied. In basal conditions up to 400 mg/l amrinone behaved as a pure chronotropic agent, raising the heart rate by 23%. In ischaemia-damaged hearts 100 mg/l amrinone had a true inotropic action, provoking significant increases in cardiac output (11%), aortic flow (10%) and double product (9%). The addition of 10 microM adenosine, which inhibits the inotropic action of catecholamines, did not modify the response to amrinone. However, when calcium was reduced from 2.5 to 1.25 mM, the inotropy of ischaemia-damaged hearts was not significantly affected by amrinone, and its chronotropic action was reduced. It is concluded that after acute ischaemic damage amrinone increases heart performance even in a poorly responsive species in which no inotropic effect can be produced under basal conditions. In this model its action is resistant to adenosine but depends on the availability of a sufficient amount of extracellular calcium.
Zucchi
R
R
Institute of Cardiology, University of Pisa, Italy.
Poddighe
R
R
Mariani
M
M
Ronca
G
G
D000241:Adenosine / Q000494:pharmacology*; D000676:Amrinone / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002302:Cardiac Output / Q000187:drug effects; D003327:Coronary Disease / Q000503:physiopathology*; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D006996:Hypocalcemia / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains
D000676:Amrinone; D000241:Adenosine; D002118:Calcium