HUP30 inhibits phenylephrine induced aortic contraction with an IC50 value of 3.9 μ M. HUP30 (100 μ M) increases cGMP levels in the aorta stimulated by adrenaline. HUP30 has an antispasmodic effect on the 25/30 mM K+constricted rat aortic ring, with an IC50 value of 7.5 μ M. HUP30 (3-100 μ M) inhibits phenylephrine induced extracellular Ca2+ influx and Ca2+ mobilization. HUP30 (10-100 μ M) inhibits current in single tailed artery muscle cells [1].