Reproducibility andconsistency oftheresponsestosupine bicycle ergometry; evaluation inconjunction with1- adrenoceptor occupancies

A protocol ispresented forsupine bicycle ergometry inhealthy subjects, whichaims fora target increase ofheart rate(HR= 140beatsmin-') after 4mincycling under constantload. Therequired loadisselected fromapre-study ergometry withstepwise increasing load. Repeated testing withthisprotocol was showntoyield highly reproducible ergometric HR-responses. Becauseoftheirhighreliability, theergometric endpoints andincrements permit a highly sensitive comparison of,13-adrenoceptor antagonism acrossdoseandtimewithin a givencompound. Therelationship between thechanges oftheergometric riseofHR andthePi-adrenoceptor occupancy(estimatedfromradioreceptor assaydata) permits toevaluate theergometric efficiency of different P-adrenoceptor antagonists acrosstimeanddosesandtoidentify eventual differences thatdonotrelate primarily totheextentof 13i-adrenoceptor antagonism itself.