NS-1619 is a selective large conductance Ca2+-activated K+-channel activator.IC50 value: Target: Ca2+-activated K+-channel activatorNS 1619 (3-100 microM) produced a concentration-dependent inhibition of spontaneous activity in rat portal vein characterized by a reduction in the amplitude and duration of the tension waves. This inhibition was slightly potentiated in the presence of either charybdotoxin (250 nM) or penitrem A (1 microM) [1]. NS-1619 induced concentration-dependent activation of BKCa channels with a calculated EC50 of 32 microM. The NS 1619-induced activity was dependent on the presence of free Ca2+ at the intracellular surface, but was not associated with a change in channel voltage sensitivity [2]. NS 1619 (50 microM) inhibited the noradrenaline-induced contraction. NS 1619 (10-100 microM) reduced the high K+-induced contractions in a noncompetitive manner [3]. Inhalation of a 12 μM and 100 μM NS1619 solution significantly reduced RV pressure without affecting systemic arterial pressure. Blood gas analyses demonstrated significantly reduced carbon dioxide and improved oxygenation in NS1619-treated animals pointing towards a considerable pulmonary shunt-reducing effect. In PASMC's, NS1619 (100 μM) significantly attenuated PASMC proliferation by a pathway independent of AKT and ERK1/2 activation [4].

References:
[1]. Edwards G, et al. Ion channel modulation by NS 1619, the putative BKCa channel opener, in vascular smooth muscle. Br J Pharmacol. 1994 Dec;113(4):1538-47.
[2]. Lee K, et al. NS 1619 activates BKCa channel activity in rat cortical neurones. Eur J Pharmacol. 1995 Jul 4;280(2):215-9.
[3]. Huang Y, et al. NS 1619 activates Ca2+-activated K+ currents in rat vas deferens. Eur J Pharmacol. 1997 Apr 23;325(1):21-7.
[4]. Revermann M, et al. Inhalation of the BK(Ca)-opener NS1619 attenuates right ventricular pressure and improves oxygenation in the rat monocrotaline model of pulmonary hypertension. PLoS One. 2014 Jan 31;9(1):e86636.