“Double reciprocal plot of noradrenaline output against the Ca2+ concentration used for stimulation (….9–7.2 mM; α-adrenoceptors and neuronal uptake blocked by phentolamine and cocaine , respectively) yielded a straight line (Km=1.… mM Ca2+), and the inhibition by verapamil proved to be competitive (…=8.8 μM verapamil).”