Analysis of cardiac chronotropic responses to diazepam and bromazepam in conscious trained dogs
In conscious trained dogs, administration of bromazepam (0.3 mg/kg p.o.) or diazepam (0.3 and 1.0 mg/kg p.o.) had no influence on heart rate. A higher dose (10 mg/kg p.o.) of two benzodiazepines elicited a positive chronotropic effect which was rapid in onset and of long duration. The beta-adrenoceptor blocking agent practolol (2.5 mg/kg i.v.) did not revert heart rate after the benzodiazepines to the same level as in controls, indicating that the tachycardia was not produced by an increase in sympathetic outflow to the heart. For diazepam, a sympathetic--parasympathetic interaction cannot be excluded. However, diazepam and bromazepam significantly reduced the tachycardia which is normally observed after administration of methylatropine (0.5 mg/kg i.v.) alone or in combination with practolol. In anaesthetized dogs, bromazepam failed to modify the heart rate responses to electrical stimulation of cardiac vagal or sympathetic nerves, excluding an action on this compound on ganglionic transmission and cardiac cholinoceptors and adrenoceptors. It is concluded that high doses of diazepam and bromazepam influence the heart rate of conscious dogs in a biphasic way. Firstly, they cause a central reduction of vagal tone to the heart resulting in tachycardia. Secondly, the two drugs decrease the cardiac pacemaker rate directly. Since the overall effect is tachycardia, the central action is more pronounced.
| Medienart: |
Artikel |
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| Erscheinungsjahr: |
1976 |
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| Erschienen: |
1976 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:35 |
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| Enthalten in: |
European journal of pharmacology - 35(1976), 2 vom: 09. Feb., Seite 361-8 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Gerold, M [VerfasserIn] |
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| Themen: |
7C0697DR9I |
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| Anmerkungen: |
Date Completed 19.04.1976 Date Revised 23.06.2019 published: Print Citation Status MEDLINE |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM000029793 |
|---|
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| 100 | 1 | |a Gerold, M |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Analysis of cardiac chronotropic responses to diazepam and bromazepam in conscious trained dogs |
| 264 | 1 | |c 1976 | |
| 336 | |a Text |b txt |2 rdacontent | ||
| 337 | |a ohne Hilfsmittel zu benutzen |b n |2 rdamedia | ||
| 338 | |a Band |b nc |2 rdacarrier | ||
| 500 | |a Date Completed 19.04.1976 | ||
| 500 | |a Date Revised 23.06.2019 | ||
| 500 | |a published: Print | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a In conscious trained dogs, administration of bromazepam (0.3 mg/kg p.o.) or diazepam (0.3 and 1.0 mg/kg p.o.) had no influence on heart rate. A higher dose (10 mg/kg p.o.) of two benzodiazepines elicited a positive chronotropic effect which was rapid in onset and of long duration. The beta-adrenoceptor blocking agent practolol (2.5 mg/kg i.v.) did not revert heart rate after the benzodiazepines to the same level as in controls, indicating that the tachycardia was not produced by an increase in sympathetic outflow to the heart. For diazepam, a sympathetic--parasympathetic interaction cannot be excluded. However, diazepam and bromazepam significantly reduced the tachycardia which is normally observed after administration of methylatropine (0.5 mg/kg i.v.) alone or in combination with practolol. In anaesthetized dogs, bromazepam failed to modify the heart rate responses to electrical stimulation of cardiac vagal or sympathetic nerves, excluding an action on this compound on ganglionic transmission and cardiac cholinoceptors and adrenoceptors. It is concluded that high doses of diazepam and bromazepam influence the heart rate of conscious dogs in a biphasic way. Firstly, they cause a central reduction of vagal tone to the heart resulting in tachycardia. Secondly, the two drugs decrease the cardiac pacemaker rate directly. Since the overall effect is tachycardia, the central action is more pronounced | ||
| 650 | 4 | |a Journal Article | |
| 650 | 7 | |a Anti-Anxiety Agents |2 NLM | |
| 650 | 7 | |a Atropine Derivatives |2 NLM | |
| 650 | 7 | |a Atropine |2 NLM | |
| 650 | 7 | |a 7C0697DR9I |2 NLM | |
| 650 | 7 | |a Diazepam |2 NLM | |
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| 650 | 7 | |a Practolol |2 NLM | |
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| 650 | 7 | |a Bromazepam |2 NLM | |
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| 700 | 1 | |a Cavero, I |e verfasserin |4 aut | |
| 700 | 1 | |a Riggenbach, H |e verfasserin |4 aut | |
| 700 | 1 | |a Wall, M |e verfasserin |4 aut | |
| 700 | 1 | |a Haeusler, G |e verfasserin |4 aut | |
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