The Role Of Calcium (Ca++) and Magnesiurn (Mg++) lons on The Endothetium-Dependent Relaxation of Rabbit Aorta

In this in vitro study it was investigated how much the ACh responses, which obtained after NA contractions in rabb it thorasic aorta preparations with endothelium or withouz endothelium, depends on the concentrations of Ca++ and Mg++ ions in the medium. in peraparation with intact endothelium, Ach inhibited the contractile effect of 10-9M NA on a large scala. When these ions' concentrations were reduced to halt, this inhibition decreased significantly. In Ca+ +-free er Mg++-free solution there was no inhibition. However, in preparations without endothelium and in also three mediurn, addition of ACh increased the contractile response to NA, significantly. The results suggest that there must be an intact endothelium in rabbit aorta for inhibition of . NA-mediated contractions, by ACh. Furthermore, iris demonstrated that, also preparations wıttz intact endothelium Ca++ and Mg++ ions are necessary for relaxation by ACh.