title: Antihypertensive agents have different ability to modulate arterial pressure and heart rate variability in 2K1C rats.
abstract: We examined the effect of chronic (15 days) administration of antihypertensive agents, from different pharmacologic classes, on arterial pressure (AP) and heart rate variability in two-kidney, one-clip hypertensive (2K1C) rats. The 2K1C rats received by gavage one of the following: water, ramipril, losartan, atenolol, amlodipine, or hydrochlorothiazide. Sham-operated normotensive rats received water. After 15 days of treatment AP was continuously sampled from an indwelling catheter in awake rats during a 2-h period and systolic AP and pulse interval (PI) were submitted to autoregressive spectral analysis with oscillatory components quantified in low (LF: 0.25 to 0.75 Hz) and high (HF: 0.75 to 3.0 Hz) frequency bands. The AP measured by tail-cuff was 170 +/- 2 mm Hg in 2K1C and 131 +/- 3 mm Hg in normotensive rats. Pooled data indicated that all antihypertensive agents reduced the AP of 2K1C rats to 127 +/- 2 mm Hg, whereas 2K1C rats treated with water remained hypertensive (206 +/- 11 mm Hg). Variance of systolic AP was found increased in 2K1C rats treated with water (34 +/- 2 mm Hg2), whereas 2K1C rats treated with ramipril, atenolol, amlodipine, or hydrochlorothiazide presented AP variance similar to normotensive rats (16 +/- 2 mm Hg2). Losartan normalized AP of 2K1C rats but variance of systolic AP remained increased (34 +/- 7 mm Hg2). The 2K1C rats treated with water had increased LF of systolic AP, whereas 2K1C rats treated with losartan showed higher LF of systolic AP and PI. Atenolol presented lower LF and higher HF of PI. In conclusion, losartan normalized AP but did not reduce AP variability, suggesting an autonomic imbalance characterized by higher sympathetic modulation of the cardiovascular system.
authors.affiliation: Department of Internal Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Nobre
authors.forename: Carlos Alberto Aguiar
authors.initials: CA
authors.lastname: da Silva
authors.forename: Eduardo Barbosa
authors.initials: EB
authors.lastname: Coelho
authors.forename: Helio Cesar
authors.initials: HC
authors.lastname: Salgado
authors.forename: Rubens
authors.initials: R
authors.lastname: Fazan
mesh_terms: D017311:Amlodipine / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001262:Atenolol / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002319:Cardiovascular System / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006852:Hydrochlorothiazide / Q000494:pharmacology; D006973:Hypertension / Q000503:physiopathology*; D019808:Losartan / Q000494:pharmacology; D008297:Male; D017257:Ramipril / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents; D006852:Hydrochlorothiazide; D017311:Amlodipine; D001262:Atenolol; D019808:Losartan; D017257:Ramipril