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Effects of the α1-adrenoceptor agonist phenylephrine on SART stress-induced orthostatic hypotension in rats.

Funakami Y, Itoh E, Hata T, Wada T, Ichida S - Biopsychosoc Med (2010)

Bottom Line: Blood pressure was directly measured from the left common carotid artery and ECG was recorded simultaneously.The maximum decrease in blood pressure and the area under the blood pressure-time curve were both large, while the %reflex was small in the SART-stressed rats compared with unstressed rats.The results suggested that sympathetic dysfunction is a factor underlying SART stress-induced OH.

View Article: PubMed Central - HTML - PubMed

Affiliation: Kinki University School of Pharmacy, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan. funakami@phar.kindai.ac.jp.

ABSTRACT

Background: Specific alternation of rhythm in temperature (SART)-stressed rats, an animal model of autonomic imbalance, exhibit low blood pressure and tachycardia during consciousness and under anesthesia. In addition, these rats easily develop orthostatic hypotension (OH) as a response to postural manipulation. Hence, we studied the influence of the adrenalin α1-receptor agonist phenylephrine on stress-induced OH in SART-stressed rats and unstressed rats.

Methods: Male Wistar rats weighing 250-300 g were used. Rats were fixed in the supine position under urethane anesthesia. Blood pressure was directly measured from the left common carotid artery and ECG was recorded simultaneously.

Results: The maximum decrease in blood pressure and the area under the blood pressure-time curve were both large, while the %reflex was small in the SART-stressed rats compared with unstressed rats. In the SART-stressed rats, prolonged intravenous administration of phenylephrine reduced OH at a dose that barely affected unstressed rats.

Conclusion: The results suggested that sympathetic dysfunction is a factor underlying SART stress-induced OH.

No MeSH data available.


Related in: MedlinePlus

Influence of SART stress on tilting parameters in anesthetized rats. Data show the mean ± S.E.M. from 7 unstressed rats (U, open column) and 9 SART-stressed rats (S, closed column). *P < 0.05, **P < 0.01, ***P < 0.001 vs respective unstressed group (t-test).
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Figure 2: Influence of SART stress on tilting parameters in anesthetized rats. Data show the mean ± S.E.M. from 7 unstressed rats (U, open column) and 9 SART-stressed rats (S, closed column). *P < 0.05, **P < 0.01, ***P < 0.001 vs respective unstressed group (t-test).

Mentions: Figure 2 shows resting MBP, HR, MD, %reflex and AUC with the HUT test. Resting MBP measured in the supine position was 100.5 ± 3.4 mmHg in unstressed rats, and 75.3 ± 4.5 mmHg in SART-stressed rats. HR of SART-stressed rats was 439.0 ± 20.9 beats/min, which was significantly greater than the value of 365.9 ± 8.4 beats/min in unstressed rats.


Effects of the α1-adrenoceptor agonist phenylephrine on SART stress-induced orthostatic hypotension in rats.

Funakami Y, Itoh E, Hata T, Wada T, Ichida S - Biopsychosoc Med (2010)

Influence of SART stress on tilting parameters in anesthetized rats. Data show the mean ± S.E.M. from 7 unstressed rats (U, open column) and 9 SART-stressed rats (S, closed column). *P < 0.05, **P < 0.01, ***P < 0.001 vs respective unstressed group (t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2967492&req=5

Figure 2: Influence of SART stress on tilting parameters in anesthetized rats. Data show the mean ± S.E.M. from 7 unstressed rats (U, open column) and 9 SART-stressed rats (S, closed column). *P < 0.05, **P < 0.01, ***P < 0.001 vs respective unstressed group (t-test).
Mentions: Figure 2 shows resting MBP, HR, MD, %reflex and AUC with the HUT test. Resting MBP measured in the supine position was 100.5 ± 3.4 mmHg in unstressed rats, and 75.3 ± 4.5 mmHg in SART-stressed rats. HR of SART-stressed rats was 439.0 ± 20.9 beats/min, which was significantly greater than the value of 365.9 ± 8.4 beats/min in unstressed rats.

Bottom Line: Blood pressure was directly measured from the left common carotid artery and ECG was recorded simultaneously.The maximum decrease in blood pressure and the area under the blood pressure-time curve were both large, while the %reflex was small in the SART-stressed rats compared with unstressed rats.The results suggested that sympathetic dysfunction is a factor underlying SART stress-induced OH.

View Article: PubMed Central - HTML - PubMed

Affiliation: Kinki University School of Pharmacy, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan. funakami@phar.kindai.ac.jp.

ABSTRACT

Background: Specific alternation of rhythm in temperature (SART)-stressed rats, an animal model of autonomic imbalance, exhibit low blood pressure and tachycardia during consciousness and under anesthesia. In addition, these rats easily develop orthostatic hypotension (OH) as a response to postural manipulation. Hence, we studied the influence of the adrenalin α1-receptor agonist phenylephrine on stress-induced OH in SART-stressed rats and unstressed rats.

Methods: Male Wistar rats weighing 250-300 g were used. Rats were fixed in the supine position under urethane anesthesia. Blood pressure was directly measured from the left common carotid artery and ECG was recorded simultaneously.

Results: The maximum decrease in blood pressure and the area under the blood pressure-time curve were both large, while the %reflex was small in the SART-stressed rats compared with unstressed rats. In the SART-stressed rats, prolonged intravenous administration of phenylephrine reduced OH at a dose that barely affected unstressed rats.

Conclusion: The results suggested that sympathetic dysfunction is a factor underlying SART stress-induced OH.

No MeSH data available.


Related in: MedlinePlus