I am wondering which is the best, most specific B1 agonist that is currently available. Dobutamine doesn't seem to be any good as it causes blood pressure to decrease. Thanks!
I think it would depend on the experiment and the particular parameter you are trying to measure. Consider isoprenaline or xamoterol. Also, if you are trying to do something clinically-relevant, the parasympatholytic atropine might also be worthwhile.
We use isoprenaline for bradyarrhythmias and dobutamine as inotropic. You could consider a higher dose of dobutamine or adding noradrenaline to dobutamine.