1. An inositol monophosphatase was purified to homogeneity from bovine brain. 2. The enzyme is a dimer of subunit Mr 29,000. 3. The enzyme hydrolyses both enantiomers of myo-inositol 1-phosphate and both enantiomers of myo-inositol 4-phosphate, but has no activity towards inositol bisphosphates, inositol trisphosphates or inositol 1,3,4,5-tetrakisphosphate. 4. Several non-inositol-containing monophosphates are also substrates. 5. The enzyme requires Mg2+ for activity, and Zn2+ supports activity to a small extent. 6. Other bivalent cations (including Zn2+) are inhibitors, competitive with Mg2+. 7. Phosphate, but not inositol, is an inhibitor competitive with substrate. 8. Li+ inhibits hydrolysis of inositol 1-phosphate and inositol 4-phosphate uncompetitively with different apparent Ki values (1.0 mM and 0.26 mM respectively).

The synthesis and biochemical evaluation of a series of indole oxadiazole 5-HT3 antagonists are described. The key pharmacophoric elements have been defined as a basic nitrogen, a linking group capable of H-bonding interactions, and an aromatic moiety. The steric limitations of the aromatic binding site have been determined by substitution about the indole ring. Variation of the heterocyclic linking group has shown that while two hydrogen-bonding interactions are possible, only one is essential for high affinity. The environment of the basic nitrogen has been investigated and shown to be optimal when constrained within an azabicyclic system. These results have been incorporated into a proposed binding model for the 5-HT3 antagonist binding site, in which the optimum distance between the aromatic binding site and the basic amine is 8.4-8.9 A and the steric limitations are defined by van der Waals difference mapping.

1 Daily administration of 1 nmol substance P or 3 pmol recombinant human interleukin-1 alpha (IL-la) caused intense neovascularization in a rat sponge model of angiogenesis. Lower doses of substance P (10 pmol) or IL-lh (0.3 pmol) were ineffective when given alone. When combined at these low doses, substance P and IL-lo interacted to produce an enhanced neovascular response.2 By use of selective tachykinin NK,, NK2 and NK3 receptor agonists, ([Sar9,Met(02)' ]substance P, [P-Ala8]neurokinin A(4-10), Succ-[Asp6,MePhe8]substance P(6-11) (senktide), respectively), it was established that the activation of NK, receptors is most likely to mediate the angiogenic response to substance P in this model.3 The angiogenic activity of substance P and IL-lh (10 pmol and 0.3 pmol day-', respectively) was abolished by co-administration of (i) the selective peptide NK, receptor antagonist, L-668, 169 (1 nmol day-'), (ii) the selective non-peptide NK, receptor antagonists, RP 67580 and (±)-CP-96,345 (both at 1 nmol day-') or (iii) the IL-1 receptor antagonist, IL-Ira, (50 g day-'). In contrast, the selective NK2 receptor antagonist, L-659,874 (1 nmol day-') was ineffective. 4 The angiogenic action of substance P and IL-lh was resistant to modification by mepyramine (1 nmol day-') and/or cimetidine (10 nmol day-'), indomethacin (7 nmol day-') or the plateletactivating factor (PAF) antagonist, WEB-2086 (22 nmol day-'), indicating that histamine, prostaglandins and PAF are not likely to be involved in this neovascular response.5 The inhibition of the substance P/IL-I angiogenic response by selective NK, receptor antagonists or by an IL-1 receptor antagonist demonstrates that angiosuppression can be achieved by blocking the activity of angiogenic factors at the receptor level.

No abstract

1 We investigated the effects of the non-peptide NK1 receptor antagonist, CP-96,345, its inactive enantiomer CP-96,344, and the racemic mixture ( ± )-CP-96,345, on the binding of [3H]-nimodipine and [3H]-diltiazem to L-type calcium channels in rat cerebral cortex membranes. In isolated peripheral tissues containing tachykinin receptors, the effects of (± )-CP-96,345 have been compared with those of diltiazem.2 In guinea-pig trachea, (± )-CP-96,345 produced antagonism of responses to the selective NK, agonists [Sar9, Met(02)"]SP and substance P-methyl ester that was apparently competitive in nature (pKB 7.0-7.5), while in guinea-pig ileum the antagonism was not surmountable. 3 The reduction of maximum responses by ( ± )-CP-96,345 in the guinea-pig ileum was not selective; it was obtained with muscarinic agonists and other agents, and was also observed in the portal vein of the rat where NK, receptors are not present. The functional effect that may be observed in integrated models will be a consequence of either property, or be a composite effect of NK, receptor antagonism and L-channel blockade.