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

<jats:p><jats:list list-type="explicit-label"> <jats:list-item><jats:p>Tachykinin‐stimulated inositol phospholipid hydrolysis was examined in slices of hamster urinary bladder.</jats:p></jats:list-item> <jats:list-item><jats:p>In the presence of lithium, to inhibit inositol monophosphatase activity, substance P, eledoisin and related tachykinins induced large, dose‐dependent increases in [<jats:sup>3</jats:sup>H]‐inositol monophosphate accumulation.</jats:p></jats:list-item> <jats:list-item><jats:p>The responses to substance P and eledoisin were not antagonized by the cholinoceptor antagonist, atropine.</jats:p></jats:list-item> <jats:list-item><jats:p>The rank order of potency for various tachykinins was kassinin ≫ neurokinin A ≫ neurokinin B ≫ eledoisin ≫ physaelamin ≫ substance P ≫ substance P methyl ester.</jats:p></jats:list-item> <jats:list-item><jats:p>The synthetic analogue [p‐Glu<jats:sup>6</jats:sup>, D‐Pro<jats:sup>9</jats:sup>] SP (6–11) was considerably more potent than its L‐prolyl stereoisomer at stimulating inositol phospholipid hydrolysis.</jats:p></jats:list-item> <jats:list-item><jats:p>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.</jats:p></jats:list-item> </jats:list></jats:p>