Effect of various neurotransmitters and electrical field stimulation on smooth muscle preparations from the esophagus of horses
| Autor: | P. Bebié, M. Denac, Erwin Scharrer |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Male
medicine.medical_specialty Contraction (grammar) Substance P Pathology and Forensic Medicine chemistry.chemical_compound Esophagus Internal medicine medicine Prazosin Animals Horses Neurotransmitter Agents General Veterinary Antagonist Muscle Smooth Electric Stimulation Atropine Endocrinology chemistry Tetrodotoxin Female Histamine Acetylcholine medicine.drug Muscle Contraction |
| Zdroj: | Zentralblatt fur Veterinarmedizin. Reihe A. 40(7) |
| ISSN: | 0514-7158 |
| Popis: | Summary The effects of various neurotransmitters and electrical field stimulation on muscle strips from the distal equine esophagus were studied. Acetylcholine (ACH) caused concentration dependent (1.1–55 · 10−6 mol/l) contractions of the longitudinal and circular muscle strips from the distal esophagus as well as from the lower esophageal sphincter (LES). Atropine (10−5 mol/l) blocked these contractions. Noradrenaline (NA) induced concentration related (1.1–55 · 10−6 mol/l) contractions of the muscle strips from the LES. This excitatory effect of noradrenaline was antagonized by the α1-receptor antagonist prazosin. Tetrodotoxin (5 · 10−6 mol/l) did not affect the contractile response of the muscle strips to noradrenaline (55 · 10−6 mol/l). Noradrenaline (1.1–55 · 10−6 mol/l) had no excitatory effect on the circular and the longitudinal muscle strips from the esophagus. Furthermore, noradrenaline induced a concentration dependent (1.1–55 · 10−6 mol/l) relaxation of the longitudinal muscle strips from the esophagus. The relaxing effect of NA was antagonized by the β-receptor antagonist propranolol (10−5 mol/l). Histamine (10−7-10−6 mol/l) elicited a contraction in 4 out of 18 muscle preparations from the LES. The histamine induced contractions were partly antagonized by the H1-receptor antagonist clemastine (10−4 mol/l) and fully abolished by the H2-receptor antagonist clemastine (10−4 mol/l). Electrical field stimulation (EFS, 5 Hz, 2 ms; 500 mA; 10 Hz, 2 ms; 500 mA) produced tetrodotoxin sensitive contractions in all three types of muscle strips. Atropine (10−5 mol/l) fully suppressed these contractions in most preparations. Prazosin (10−4 mol/l) had no effect on the contractions produced by EFS. Substance P (1–5.5 · 10−6 mol/l) serotonin (10−6-10−4 mol/l) cholecystokinin (10−5-106 mol/l), and VIP (10−8-5 · 10−7 mol/l) did not produce any effect on all three types of muscle strips. These results suggest that aceylcholine is the most important excitatory transmitter in the distal equine esophagus. |
| Databáze: | OpenAIRE |
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