which rotates the plane of oscillation of linearly polarized light of the sodium d line to the left is surprisingly the only carrier of the biological effects of cimaterol i the two enantiomers of cimaterol were subjected to comparative tests to investigate their u03b2 mimetic effects on the smooth muscle of the bronchus the skeletal musculate and the fat cells they were also compared for their acute toxicity the u03b2 mimetic effect on the smooth muscle was examined in terms of a broncholytic effect in the test designed by konsett and rossler arch exp path pharmakol 195 71 74 1940 compared with the acetyl choline induced bronchospasm in guinea pigs after i v administration from the inhibition of bronchospasm achieved with the various doses of the test substance an ed 50 was calculated by linear regression analysis as the dosage which resulted in a 50 inhibition of bronchospasm the l enantiomer is about 100 times more effective on the u03b2 receptors of the bronchus than the corresponding d enantiomer the u03b2 mimetic effect on the skeletal musculature was tested using the method of bowman and nott pharmacol rev 21 27 1969 this investigates the influence on the tension of the incompletely tetanically contracting m soleus of anaesthetized cats after i v administration ______________________________________ dose reduction in tension in substance u03bcg kg n x sd______________________________________cimaterol 0 5 5 38 3 10 8 cimaterol 0 5 5 42 1 6 0 cimaterol 50 0 5 33 7 8 0______________________________________ the l enantiomer of cimaterol is also more than 100 times more effective than the corresponding d enantiomer on the u03b2.