^^^ How can it not make sense - its called selective - not exclusive - look at the bigger picture and think about it for a minute. There are a slew of selective beta receptor agents (think beta blaockers). These agents exist for b1 - b2 - b3 receptors. Some are so selective ( even exclusive) that they are used in experimentation due to there extreme specificity. Also stop think in absolutes such as "no agonist" and stick to what i said "virtually no agonist" - ie - no clinically significant agonist activity. Also the same can be said for clens b3 agonist effects. While they exist it is to a lesser degree. Also just because cAMP is second messeneger for b1 and b2 far from means the same agonist activity is exerted on boith - you know that. I personally would say clens effects are primarily exerted on b2 ...then to a lesser extent b3 ...then minimally on b1 . Thats just my opinion - but I think its pretty damn sound based on science and experience.