“The spasmogenic activity of methylxanthines was evaluated in … 20 degrees C. The contraction elicited by caffeine …), amiloride (100 microM), staurosporine (1 microM), H-7 (50 microM), polymyxin B (500 microM), K(+)-free solution, …) solution but was unaltered in the presence of verapamil (10 microM) or vanadate (10-100 microM).”