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A study to investigate capsaicin-induced pressure response in vagotomized rats
Abhaya Dutta, Aparna Akella, Shripad B Deshpande
Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
Correspondence Address:
Shripad B Deshpande
Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh
India
Objectives: Capsaicin is used to evoke pulmonary C reflexes and produces complex pressure responses along with apnea/tachypnea, and bradycardia. In the present study, the mechanisms involved in capsaicin-induced pressure responses were explored.
Materials and Methods: Tracheal, jugular venous, and femoral artery cannulations were performed in anesthetized adult rats. Blood pressure, respiratory excursions, and electrocardiogram were recorded. Cardiorespiratory reflex changes evoked by jugular venous injection of capsaicin (10 μg/kg) were recorded in vagotomized and antagonist pretreated animals.
Results: Capsaicin produced triphasic pressure response exhibiting immediate hypotension, intermediate recovery, and delayed hypotension. Time-matched respiratory changes showed apnea, bradypnea, and tachypnea, respectively. Bradycardia occurred at immediate and intermediate phases. After vagotomy, immediate hypotension was abolished; the intermediate recovery was potentiated as hypertensive response; and the delayed hypotension persisted. In case of respiration, the immediate bradypnea persisted and delayed tachypnea was abolished; while heart rate changes at immediate and intermediate phases were abolished. Antagonists of α1 -adrenoceptor (prazosin or terazosin, 0.5 mg/kg), β-adrenoceptor (propranolol, 1 mg/kg), AT 1 receptor (losartan, 10 mg/kg) and Ca 2+ channel (diltiazem, 1 mg/kg) failed to block the capsaicin-induced intermediate hypertensive response in vagotomized animals.
Conclusions: These observations implicate the existence of mechanisms other than adrenergic, angiotensinergic, or Ca 2+ channel-dependent mechanisms for mediating the capsaicin-induced intermediate hypertensive response in vagotomized animals.
How to cite this article:
Dutta A, Akella A, Deshpande SB. A study to investigate capsaicin-induced pressure response in vagotomized rats.Indian J Pharmacol 2013;45:365-370
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How to cite this URL:
Dutta A, Akella A, Deshpande SB. A study to investigate capsaicin-induced pressure response in vagotomized rats. Indian J Pharmacol [serial online] 2013 [cited 2023 Jun 10 ];45:365-370
Available from: https://www.ijp-online.com/article.asp?issn=0253-7613;year=2013;volume=45;issue=4;spage=365;epage=370;aulast=Dutta;type=0 |
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