Effects of allocryptopine, an alkaloid isolated from Glaucium arabicum on rat isolated ileum and urinary bladder.

1. The alkaloid, allocryptopine, was isolated from the chloroform extract of Glaucium arabicum. 2. The effect of allocryptopine on urinary bladder and ileal smooth muscles was investigated in this study. 3. Allocryptopine, in concentrations from 1 x 10(-5) to 3 x 10(-3) M caused a concentration-dependent contraction of rat isolated urinary bladder and a concentration-dependent relaxation of rat ileal smooth muscles. 4. Theophylline (10(-5) M) shifted to the left the allocryptopine concentration-effect curve on ileum and increased the maximum inhibitory effect of allocryptopine. 5. Methylene blue (10(-3) M) had no significant effect on the concentration-effect curve of allocryptopine of the ileum. 6. Phentolamine (10(-6) M) shifted to the right the allocryptopine concentration-effect curve of urinary bladder. 7. These observations suggest that allocryptopine induces a relaxing effect on the ileum by inhibiting phosphodiesterase enzyme, and thus elevating cellular cAMP and its contractile effect on the urinary bladder by affecting alpha-adrenergic receptors in this tissue.