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Document Type |
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Article In Journal |
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Document Title |
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Cardiovascular Responses to Calcitonin Injection in Rats* Cardiovascular Responses to Calcitonin Injection in Rats* |
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Document Language |
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English |
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Abstract |
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This study was planned to elucidate the cardiovascular responses to calcitonin in intact rats on the hemodynamic changes as well as the electrical activity of the heart. Moreover, the isolated hearts were examined for their basal activities as well as their responses to beta adrenergic stimulation using a graded isoproterenol infusion, in order to explore the possible mechanisms of action of calcitonin on the cardiovascular system.
Rats were divided into three main groups, normal adult male albino rats were injected intraperitoneally with calcitonin in a dose of 251 U/ml/kg for single dose in the first group, for 14 consecutive days for the second group and for 30 consecutive days for the third group. Comparison was made against their matching control rats receiving distilled water in the same regimen.
Each rat was subjected to ECG recording and measurement of mean arterial blood pressure, then packed cell volume was determined and separated plasma was examined for calcium, inorganic phosphorus, total cholesterol and HDL-cholesterol as well as calculation of atherogenic index.
Isolated hearts were perfused using Langendorff technique and examined for basal activities as well as their response to isoproterenol infusion, regarding heart rate peaked developed tension, time to peak tension, half relaxation time as well as coronary blood flow per minute.
The results of this study revealed that a single administration of calcitonin resulted in a significant hypocalcemic, hyperphosphatemic response as well as asignificant increase of HDL-cholesterol. On the other hand, isolated hearts revealed that the increase in basal absolute peaked developed tension as well as absolute coronary flow was insignificant compared to their matching controls.
Administration of calcitonin for two weeks resulted in a significant hypocalcemia associated with hypo-cholestcrolemia. These changes were accompanied by an elevation of the mean arterial blood pressure.
Although the obtained tachycardia was insignificant, yet, the arterial heart rate-blood pressure product was significantly elevated. Isolated hearts revealed a significant elevation of basal heart rate accompanied by an insignificant increase in basal absolute peak developed tension. Also, basal absolute and relative coronary flow were insignificantly decreased compared to their matching controls.
On extending the duration of calcitonin injection for one month, the hypocalcemic response as well as the elevated mean arterial blood pressure and arterial blood pressure-heart rate product were maintained. The changes were accompanied by an increase in heart rate with concomitant shortening in P-R interval.
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Isolated heart studies revealed that although, the absolute peak developed tension and coronary flow were insignificantly elevated. Yet, their relative values showed a significant increase when compared to their matching controls.
In conclusion, calcitonin has a positive chronotropy and a positive ionotropy. It also increases the coronary flow rate with no hypertrophy or ischemic changes. |
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ISSN |
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0969-711 |
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Journal Name |
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Zagazig University Medical Journal |
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Volume |
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10 |
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Issue Number |
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2 |
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Publishing Year |
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2004 AH
2004 AD |
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Article Type |
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Article |
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Added Date |
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Sunday, March 21, 2010 |
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Researchers
| عاطف موسى عبود | Abood, Atef M | Researcher | Doctorate | |
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