the receptors which , upon stimulation , trigger the influx of extracellular calcium ions are alpha-adrenoceptors of both subtypes ( alpha 1/alpha 2 ) , although the role of alpha 2-adrenoceptors can be understood more readily than that of the alpha 1-subtype .
C0034784
alpha-adrenoceptors
C0001639
alpha 2-adrenoceptors