DA 4626 is H2-receptor antagonism. The compound which was investigated in a wider concentration range, behaved as simple competitive antagonists, yielding apparent KB values comparable with those estimated in conventional H2-receptor assays.
Small Cardioactive Peptide B (SCPB), a neurally active peptide, stimulates adenylatecyclase activity in particulate fractions of both heart and gill tissues with EC50s of 0.1 and 1.0 μM, respectively.
Pituitary adenylatecyclase-activating peptide (PACAP) (6-27) is a PACAP receptor antagonist with IC50 values of 1,500, 600, and 300 nM, respectively, for rat PAC1, rat VPAC1, and human VPAC2 recombinant receptors expressed in CHO cells. It binds to PACAP receptors on SH-SY5Y and SK-N-MC human neuroblastoma and T47D human breast cancer cells (IC50s = 24.5, 106, and 105 nM, respectively) and inhibits cAMP accumulation induced by PACAP (1-38) (Kis = 457, 102, and 283 nM, respectively, in SH-SY5Y, SK-N-MC, and T47D cells). In vivo, in newborn pigs, PACAP (6-27) (10 μM) inhibits vasodilation of pial arterioles induced by PACAP (1-27) and PACAP (1-38) . It also inhibits PACAP (1-27)-stimulated increases in plasma insulin and glucagon levels and pancreatic venous blood flow in dogs when administered locally to the pancreas at a dose of 500 μg.
Deacetylforskolin is a diterpene and a derivative of forskolin that has been found inC. forskohliiand has diverse biological activities.1,2,3,4It activates rat adipocyte adenylyl cyclase (IC50= 20 μM) and inhibits glucose transport in rat adipocyte plasma membranes.2Deactylforskolin (30-1,000 μg kg) reduces blood pressure in spontaneously hypertensive rats.3It also attenuates hypercapnia-induced impairments in the passive avoidance response in mice.4 1.Gabetta, B., Zini, G., and Danieli, B.Minor Diterpenoids of Coleus forskohliiPhytochemistry28(3)859-862(1989) 2.Joost, H.G., Habberfield, A.D., Simpson, I.A., et al.Activation of adenylatecyclase and inhibition of glucose transport in rat adipocytes by forskolin analogues: structural determinants for distinct sites of actionMol. Pharmacol.33(4)449-453(1988) 3.Bhat, S.V., Dohadwalla, A.N., Bajwa, B.S., et al.The antihypertensive and positive inotropic diterpene forskolin: Effects of structural modifications on its activityJ. Med. Chem.26(4)486-492(1983) 4.McCulloch, A.J., Thomson, T.A., and Deacon, R.Hypoxic amnesia and its reversal with forskolinBiochem. Soc. Trans.17(1)212-213(1988)