Dose-dependent reduction of myocardial infarct mass in rabbits by the NHE-1 inhibitor cariporide (HOE 642).
The aim of this study was to investigate the dose-dependent effect of pretreatment with the selective sodium-hydrogen exchange NHE-subtype 1 inhibitor cariporide on myocardial infarct mass in a rabbit model of coronary ligation and reperfusion. Furthermore, in a second part of the study, we tested the effect of cariporide in the rabbits when given prior to reperfusion. Rabbits (n=49) were randomized in 7 groups: saline vehicle, cariporide: 0.01, 0.03, 0.1 and 0.3 mg/kg, and subjected to a 30 min occlusion of a branch of the left coronary artery followed by 2 h reperfusion. Cariporide was given as a bolus intravenously 10 min before occlusion or 5 min before reperfusion. After reperfusion, myocardial infarct mass was determined by triphenyl tetrazolium chloride staining and expressed as a percent of area at risk. Cariporide given intravenously 10 min before occlusion in doses of 0.01, 0.03, 0.1, 0.3 mg/kg, led to a dose-dependent reduction in infarct mass from 58+/-6% in controls to 48+/-4% (-17%, NS), 36+/-5% (-38%, p<0.05), 26+/-6% (-55%, p<0.05), 11+/-4% (-81%, p<0.05) respectively, whereas area at risk did not differ in between the groups. The effect of the lowest dose of 0.01 mg/kg did not reach significance. Plasma levels at different doses of cariporide were correlated to the respective infarct mass. After coronary occlusion left ventricular end-diastolic pressure (LVEDP) significantly increased throughout occlusion and reperfusion. Cariporide in the doses of 0.3, 0.1 and 0.03 mg/kg normalized LVEDP when measured after 2 h reperfusion. In controls hemodynamic parameters such as mean arterial blood pressure (MAP), heart rate (HR), left ventricular pressure (LVP) and LV dP/dt(max) were not significantly changed by ischemia/reperfusion with the exception of MAP, LVP and LV dP/dt(max) which were significantly decreased after 120 min reperfusion. Cariporide at doses of 0.1, 0.03 and 0.01 mg/kg did not significantly influence these parameters, whereas the highest dose of 0.3 mg/kg prevented the decrease of MAP and LVP. Cariporide (0.3 mg/kg i.v.) administered 5 min before reperfusion significantly reduced infarct mass by 31%. Under these conditions the increase of LVEDP after coronary occlusion was not influenced by cariporide. As in the pretreatment experiments, the decrease of MAP and LVP was prevented when measured 2 h after reperfusion. The results show that pretreatment with the NHE-subtype 1 inhibitor cariporide is cardioprotective by reducing infarct mass in rabbits in a dose-dependent manner. While the cardioprotective effect of pretreatment could be demonstrated over a broad range of doses, the efficacy of the compound when given only on reperfusion was significant but more limited.
Hoechst Marion Roussel, DG Cardiovascular Research, Frankfurt/Main, Germany. wolfgang.linz@hmrag.com
W
W
Linz
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U
Albus
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P
Crause
W
W
Jung
A
A
Weichert
B A
BA
Schölkens
W
W
Scholz
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D005260:Female; D006146:Guanidines / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D009203:Myocardial Infarction / Q000097:blood / Q000188:drug therapy* / Q000473:pathology*; D015425:Myocardial Reperfusion; D011817:Rabbits; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors*; D013450:Sulfones / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*
D006146:Guanidines; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C069139:growth factor-activatable Na-H exchanger NHE-1; C093373:cariporide