title: Spontaneous contractions of intestinal smooth muscle re-aggregates from the new-born rat triggered by thromboxane A2.
abstract: Isolated smooth muscle cells from the small intestine of new-born rats were prepared by enzymatic digestion. These cells re-aggregate after 1 day in culture to clusters. The re-aggregates show spontaneous rhythmical contractions at 37 degrees C with a frequency (13.1 +/- 0.8 min-1, n = 49), which is similar to that of the intact smooth muscle layer. The cholinergic agonist carbachol (5 x 10(-5) mol l-1) caused an increase in the frequency of the spontaneous contractions often ending in a permanent contraction. A similar effect was achieved with the thromboxane A2 (TXA2) agonist, U-46619 (10(-5) mol l-1). In contrast, both the TXA2 receptor blocker, Bay u3405 (5 x 10(-4) mol l-1), as well as the Ca2+ channel blocker, verapamil (5 x 10(-5) mol l-1), suppressed the spontaneous contractions. The observed contractility was insensitive against the neuronal blocker tetrodotoxin (10(-6) mol l-1). These analyses of video images were supported by the measurement of relative changes in the intracellular Ca2+ concentration with the Ca(2+)-sensitive dye, fura-2. Spontaneous contractions were paralleled by spikes in the intracellular Ca2+ concentration, which were abolished by Bay u3405, but stimulated by U-46619 or carbachol. In summary, these results obtained at re-aggregates of intestinal smooth muscle cells support the hypothesis of a role of TXA2 in the generation of spontaneous intestinal smooth muscle contractions in vitro.
authors.affiliation: Institut für Veterinär-Physiologie, Justus-Liebig-Universität Giessen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Frings
authors.forename: G
authors.initials: G
authors.lastname: Haschke
authors.forename: B
authors.initials: B
authors.lastname: Heinke
authors.forename: K H
authors.initials: KH
authors.lastname: Schäfer
authors.forename: M
authors.initials: M
authors.lastname: Diener
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000032:analysis / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D002449:Cell Aggregation; D018679:Cholinergic Agonists / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000737:chemistry; D016257:Fura-2 / Q000737:chemistry; D007421:Intestine, Small / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008856:Microscopy, Fluorescence; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D051381:Rats; D013449:Sulfonamides / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002227:Carbazoles; D018679:Cholinergic Agonists; D005456:Fluorescent Dyes; D010975:Platelet Aggregation Inhibitors; D013449:Sulfonamides; D014662:Vasoconstrictor Agents; D013779:Tetrodotoxin; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D002217:Carbachol; D014700:Verapamil; C063119:ramatroban; D002118:Calcium; D016257:Fura-2