An ionotropic effect is a special kind of effect of a hormone on its target. The hormone activates or deactivates ionotropic receptors (ligand-gated ion channels). The effect can be either positive or negative, whether the effect is a depolarization or a hyperpolarization respectively.
Noradrenaline (aka. Norepinephrine) has a positive ionotropic effect on heart muscle, when binding to beta-1 adrenergic receptors on this tissue.[1] The result is an increased cardiac output.