Study of association of aerobic physical training with aerobic different pharmacological therapies on cardiovascular autonomic adaptations in spontaneously hypertensive rats (SHR)

Author(s)

Karina Delgado Maida

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2016-02-02

Examining board members

Hugo Celso Dutra de Souza; Kátia de Angelis Lobo D'Avila; Rubens Fazan Júnior; Andre Schmidt; Valdo José Dias da Silva

• Advisor: Hugo Celso Dutra de Souza

Abstract

We investigated in spontaneously hypertensive rats (SHR) young (28 weeks) and old (52 weeks) hemodynamic and autonomic cardiovascular effects caused by different pharmacological antihypertensive therapy associated with aerobic exercise. For that purpose, 18-weeks-old SHR (N = 128) were divided into four groups (N = 32): Water treated (Vehicle Group); treated with Enalapril; treated with Losartan; and treated with Amlodipine. Each group was subdivided into two smaller groups (N = 16) treated for 10 or 34 weeks, with half of each group (N = 08) was also subjected to physical training through swimming the same period of time (10 or 34 weeks). On the last day of treatment all animals were cannulated the femoral artery and vein to record blood pressure (AP) and injection of drugs, respectively. 24 hours after cardiovascular autonomic assessment was performed by means of different approaches; evaluation of sympathetic / vagal balance through double cardiac autonomic blockade with atropine and propranolol; analysis of heart rate variability (HRV) and systolic blood pressure (SAPV) by means of spectral analysis; and analysis of spontaneous baroreflex sensitivity (BRS). All treatments promoted AP reduction, however, in youth groups, treatment with Enalapril promoted the greatest reductions, regardless of physical training, while in the older groups, the association of physical training to Enalapril promoted additionally reduce AP. Regarding the cardiovascular autonomic control, treatment with Amlodipine produced greater beneficial adaptations in sedentary young group compared to other drugs, characterized by the predominance of vagal autonomic tone, increased variance in HRV, and increase in BRS. While physical training has promoted some beneficial adjustments when used alone, it was unable to potentiate the findings observed for Amlodipine. Treatment with Enalapril and Losartan promoted lower cardiovascular autonomic adaptations when administered in sedentary SHR compared to Amlodipine, however when Enalapril was associated with physical training we observed significant improvement in cardiovascular autonomic control in the different evaluated parameters, including the reduction of low-frequency oscillations (LF; 0,75-2.5Hz) in SAPV, besides an increase in the BRS. In contrast, Amlodipine alone did not modify the cardiovascular autonomic parameters in the old SHR, leaving the Enalapril and Losartan promote better effects when applied alone in these animals. Physical training also promoted beneficial autonomic adaptations in old SHR, and in some parameters, such as HRV, adjustments were even better. Surprisingly, when combined with Amlodipine, adaptations have been even more significant, with significant attenuation of the sympathetic autonomic tone, decreased sympathetic modulation and increased vagal modulation on HRV as well as reduction in the LF oscillations in SAPV and increased BRS. In conclusion, in young animals Amlodipine was more effective in promoting beneficial cardiovascular autonomic adaptations, while Enalapril showed similar autonomic results only when combined with aerobic exercise. In turn, in old animals Amlodipine had little effect on the cardiovascular autonomic control, while Losartan and Enalapril were more effective. In this case, our findings indicate that aging is a factor that interferes with cardiac autonomic control and mitigate the effects of different pharmacological treatments. Finally, physical training has a key role in the treatment of hypertension, participating in this process as a catalyst of cardiovascular autonomic effects caused by drug treatment in both, young SHR, when combined with Enalapril, as in old SHR, when associated with Amlodipine. (AU)

• FAPESP's process: 13/02880-8 - Study of the association of aerobic exercise with different pharmacological therapies on cardiac autonomic adaptations in Spontaneously Hypertensive Rats (SHR)
• Grantee: Karina Delgado Maida
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)