Effects of a new cholecystokinin antagonist (GE 410) on the smooth muscle of the guinea pig ileum

Suc-Tyr-(SE)-Met-Gly-Trp-Met-Asp-beta-phenethylamide (GE 410) competitively antagonized the contractions of smooth muscle strips from guinea pig ileum (pA2 = 7.6, n = 0.95) induced by cholecystokinin-octapeptide (CCK8). GE 410 inhibited the electrically-induced cholinergically mediated contractile responses and the [3H]ACh release in the ileum, as well as the CCK-stimulated electrical contractile responses and the [3H]ACh release in the cholinergic nerve terminals. The results suggest the existence of CCK-receptors not only in the smooth muscles but also on the neurons.     

Calyculin a increases voltage-dependent inward current in,smooth muscle cells isolated from guinea pig taenia coli

The effects of a potent phosphatase inhibitor, calyculin A (CL-A), on inward currents in guinea pig taenia coli smooth muscle cells were examined. CL-A increased the inward current, and this effect of CL-A was inhibited by a protein kinase C inhibitor, H-7, and by nifedipine. Phorbol 12,13-dibutyrate, an activator of protein kinase C, also increased the inward current and this effect was antagonized by H-7. These results suggest that in guinea pig taenia coli smooth muscle cells CL-A may facilitate the opening of thel-type Ca²⁺ channels through the protein kinase C-dependent phosphorylation system.     

Pre-and post-natal ontogeny of neutral endopeptidase 24-11 (‘enkephalinase’) studied by in vitro autoradiography in the rat

Neutral endopeptidase (NEP, enkephalinase, CALLA) which is present in various neural and non-neural tissues, is able to cleave a variety of regulatory peptides. The distribution of NEP has been studied during rat pre-and post-natal development by autoradiography after in vitro binding of the tritiated inhibitor [³H]HACBO-Gly to whole-body and organ sections. In the central nervous system (CNS), where the presence of NEP has been related to the termination of the action of enkephalins, the external layer of the olfactory bulbs is the only structure prominently labeled before birth. Other CNS structures rich in NEP in the adult, such as the nigrostriatal tract, are progressively labeled after birth. Outside the CNS, the progressive appearance of NEP in the kidney, the lungs and the salivary glands suggests its concomitant involvement in adult physiological functions, including fluid balance control, possibly by cleaving the atrial natriuretic peptide (ANP) and other peptides. On the other hand, transient or enhanced expression of NEP is observed during the development of several organs such as the sensory organs, the heart and the major blood vessels, the intestine, the bones and the genital tubercle. In addition to the still incompletely known physiological functions of the enzyme, the developmental pattern of its expression in several tissues strongly suggests a modulatory role for NEP in the ontogeny of a large number of organs.     

Effects of TA [4-ethoxy-1-(p-tolyl)-s-triazine-2,6-(1H, 3H)-dione] on growth,antheridium differentiation and gibberellin uptake of gametophytes ofAnemia phyllitidis L. Sw.

Summary Synergistic effects of TA on gibberellin-dependent reactions in spermatophytes are not detectable in gametophytes of the fernAnemia phyllitidis where gibberellin substitutes for antheridiogens with regard to induction of male sexual organs and dark germination. In this archegoniate TA caused a significant reduction in growth rate and morphogenesis of the gametophytes, inhibitions that were not abolished by simultaneous application of gibberellin.