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Effect of losartan, an angiotensin II type 1 receptor antagonist on cardiac autonomic functions of rats during acute and chronic inhibition of nitric oxide synthesis.
Physiol Res. 2012; 61(2):135-44.PR

Abstract

We studied the effect of losartan on baroreflex sensitivity (BRS) and heart rate variability (HRV) of adult Wistar rats during acute and chronic inhibition of nitric oxide synthesis by N(G)-nitro-L-arginine methyl ester (L-NAME). Chronic L-NAME administration (50 mg/kg per day for 7 days, orally through gavage) increased mean arterial pressure (MAP), heart rate but significantly decreased BRS. In addition, a significant fall of standard deviation of normal RR intervals, total spectral power, high frequency spectral power and a rise of low frequency to high frequency (LF: HF) ratio was seen. Acute L-NAME administration (30 mg/kg, i.v. bolus dose) also raised MAP and impaired HRV but it was associated with augmented BRS for bradycardia reflex. Losartan treatment (10 mg/kg, i.v.) in both acute and chronic L-NAME treated rats, decreased MAP but the difference was not significant. On the other hand, losartan administration normalized depressed BRS for bradycardia reflex and significantly reduced LF to HF ratio in chronic L-NAME treated rats. But this improvement was not observed in acute L-NAME group. These results indicate importance of mechanisms other than renin-angiotensin system in the pressor response of both acute as well as chronic L-NAME. However, autonomic dysregulation especially following chronic L-NAME appears to be partly angiotensin dependent.

Authors+Show Affiliations

Department of Physiology, Vardhaman Mahavir Medical College & Safdarjung Hospital, New Delhi, India.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22292721

Citation

Chaswal, M, et al. "Effect of Losartan, an Angiotensin II Type 1 Receptor Antagonist On Cardiac Autonomic Functions of Rats During Acute and Chronic Inhibition of Nitric Oxide Synthesis." Physiological Research, vol. 61, no. 2, 2012, pp. 135-44.
Chaswal M, Das S, Prasad J, et al. Effect of losartan, an angiotensin II type 1 receptor antagonist on cardiac autonomic functions of rats during acute and chronic inhibition of nitric oxide synthesis. Physiol Res. 2012;61(2):135-44.
Chaswal, M., Das, S., Prasad, J., Katyal, A., Mishra, A. K., & Fahim, M. (2012). Effect of losartan, an angiotensin II type 1 receptor antagonist on cardiac autonomic functions of rats during acute and chronic inhibition of nitric oxide synthesis. Physiological Research, 61(2), 135-44.
Chaswal M, et al. Effect of Losartan, an Angiotensin II Type 1 Receptor Antagonist On Cardiac Autonomic Functions of Rats During Acute and Chronic Inhibition of Nitric Oxide Synthesis. Physiol Res. 2012;61(2):135-44. PubMed PMID: 22292721.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of losartan, an angiotensin II type 1 receptor antagonist on cardiac autonomic functions of rats during acute and chronic inhibition of nitric oxide synthesis. AU - Chaswal,M, AU - Das,S, AU - Prasad,J, AU - Katyal,A, AU - Mishra,A K, AU - Fahim,M, Y1 - 2012/01/31/ PY - 2012/2/2/entrez PY - 2012/2/2/pubmed PY - 2013/7/3/medline SP - 135 EP - 44 JF - Physiological research JO - Physiol Res VL - 61 IS - 2 N2 - We studied the effect of losartan on baroreflex sensitivity (BRS) and heart rate variability (HRV) of adult Wistar rats during acute and chronic inhibition of nitric oxide synthesis by N(G)-nitro-L-arginine methyl ester (L-NAME). Chronic L-NAME administration (50 mg/kg per day for 7 days, orally through gavage) increased mean arterial pressure (MAP), heart rate but significantly decreased BRS. In addition, a significant fall of standard deviation of normal RR intervals, total spectral power, high frequency spectral power and a rise of low frequency to high frequency (LF: HF) ratio was seen. Acute L-NAME administration (30 mg/kg, i.v. bolus dose) also raised MAP and impaired HRV but it was associated with augmented BRS for bradycardia reflex. Losartan treatment (10 mg/kg, i.v.) in both acute and chronic L-NAME treated rats, decreased MAP but the difference was not significant. On the other hand, losartan administration normalized depressed BRS for bradycardia reflex and significantly reduced LF to HF ratio in chronic L-NAME treated rats. But this improvement was not observed in acute L-NAME group. These results indicate importance of mechanisms other than renin-angiotensin system in the pressor response of both acute as well as chronic L-NAME. However, autonomic dysregulation especially following chronic L-NAME appears to be partly angiotensin dependent. SN - 1802-9973 UR - https://www.unboundmedicine.com/medline/citation/22292721/Effect_of_losartan_an_angiotensin_II_type_1_receptor_antagonist_on_cardiac_autonomic_functions_of_rats_during_acute_and_chronic_inhibition_of_nitric_oxide_synthesis_ L2 - http://www.biomed.cas.cz/physiolres/pdf/61/61_135.pdf DB - PRIME DP - Unbound Medicine ER -