in the heart-lung preparation , mean 50 % beta-blocking doses of the beta-blockers to inhibit the positive chronotropic action of isoproterenol were 3.75 micrograms for nadolol , 12.5 micrograms for alprenolol , 9.6 micrograms for propranolol and 1.6 micrograms for pindolol .
C1372804
positive chronotropic
C0022245
isoproterenol