Electrophysiological and contractile responses of canine atrial tissue to adrenocorticotropin
| Autor: | Robert H. Zeiler, Nabil El-Sherif, Fleur L. Strand |
|---|---|
| Rok vydání: | 1982 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Adrenergic receptor Physiology Receptors Cell Surface Propranolol Peptide hormone Biology Biochemistry Norepinephrine Cellular and Molecular Neuroscience Dogs Endocrinology Adrenocorticotropic Hormone Internal medicine Cyclic AMP medicine Animals ACTH receptor Heart Atria Receptor Myocardium Antagonist Radioimmunoassay Atrial Function Myocardial Contraction Electric Stimulation Electrophysiology Receptors Corticotropin Catecholamine Female hormones hormone substitutes and hormone antagonists medicine.drug |
| Zdroj: | Peptides. 3:815-822 |
| ISSN: | 0196-9781 |
| Popis: | The direct extra-adrenal actions of adrenocorticotropin 1–39 (ACTH) on electrical (E) and mechanical (M) characteristics of canine atrial tissues (AT) were investigated in in vitro experiments. One hundred twenty-five mU/ml of ACTH 1–39 significantly augmented the catecholamine induced positive inotropism as seen by shortening the time to peak tension (10.6%, p =0.01) and increasing peak isometric tension (3.5 times, p =0.001). Effects on the M responses were inhibited by propranolol (10 −6 M) (P). ACTH did not significantly modify action potential E or M parameters during cholinergic receptor antagonism or alpha-adrenergic receptor antagonism. Existence of a specific ACTH receptor was demonstrated using 125 I radioiodinated ACTH 1–24. Significant binding of 125 I-ACTH to AT was observed. Intracellular C-AMP levels were also measured in AT using radioimmunoassay. Tissues were exposed to 125 mU/ml ACTH 1–39 plus combinations of norepinephrine (10 −6 M) (NE) and P. ACTH alone did not elevate intracellular C-AMP levels. NE increased C-AMP levels were not further increased by ACTH. Exposure to antagonist returned elevated C-AMP levels to control values. In conclusion (1) ACTH augments the NE induced M positive inotropism of the beta adrenergic receptor system, (2) ACTH specifically binds to AT and (3) ACTH does not utilize the C-AMP second messenger system. |
| Databáze: | OpenAIRE |
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