Effects of tachykinins on inositol phospholipid hydrolysis in slices of hamster urinary bladder

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Abstract
1 Tachykinin-stimulated inositol phospholipid hydrolysis was examined in slices of hamster urinary bladder. 2 In the presence of lithium, to inhibit inositol monophosphatase activity, substance P, eledoisin and related tachykinins induced large, dose-dependent increases in [3H]-inositol monophosphate accumulation. 3 The responses to substance P and eledoisin were not antagonized by the cholinoceptor antagonist, atropine. 4 The rank order of potency for various tachykinins was kassinin ≫ neurokinin A ≫ neurokinin B ≫ eledoisin ≫ physaelamin ≫ substance P ≫ substance P methyl ester. 5 The synthetic analogue [p-Glu6, D-Pro9] SP (6–11) was considerably more potent than its L-prolyl stereoisomer at stimulating inositol phospholipid hydrolysis. 6 These results suggest that in the hamster urinary bladder, tachykinin-induced inositol phospholipid breakdown is mediated via tachykinin receptors of the SP-E type, as opposed to the SP-P type.