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. 2018 Aug;111(2):172-179.
doi: 10.5935/abc.20180113. Epub 2018 Jul 2.

Physical Exercise and Regulation of Intracellular Calcium in Cardiomyocytes of Hypertensive Rats

[Article in English, Portuguese]
Joel Alves Rodrigues  1 , Thales Nicolau Prímola-Gomes  1 , Leôncio Lopes Soares  1 , Tiago Ferreira Leal  1 , Clara Nóbrega  2 , Danillo Laviola Pedrosa  1 , Leonardo Mateus Teixeira Rezende  1 , Edilamar Menezes de Oliveira  2 , Antonio Jose Natali  1
Affiliations

Physical Exercise and Regulation of Intracellular Calcium in Cardiomyocytes of Hypertensive Rats

[Article in English, Portuguese]
Joel Alves Rodrigues et al. Arq Bras Cardiol. 2018 Aug.

Abstract

Background: Regulation of intracellular calcium (Ca2+) in cardiomyocytes is altered by hypertension; and aerobic exercise brings benefits to hypertensive individuals.

Objective: To verify the effects of aerobic exercise training on contractility and intracellular calcium (Ca2+) transients of cardiomyocytes and on the expression of microRNA 214 (miR-214) in the left ventricle of spontaneously hypertensive rats (SHR).

Methods: SHR and normotensive Wistar rats of 16 weeks were divided into 4 groups -sedentary hypertensive (SH); trained hypertensive (TH); sedentary normotensive (SN); and trained normotensive (TN). Animals of the TH and TN groups were subjected to treadmill running program, 5 days/week, 1 hour/day at 60-70% of maximum running velocity for 8 weeks. We adopted a p ≤ 0.05 as significance level for all comparisons.

Results: Exercise training reduced systolic arterial pressure in hypertensive rats. In normotensive rats, exercise training reduced the time to 50% cell relaxation and the time to peak contraction and increased the time to 50% decay of the intracellular Ca2+ transients. In SHR, exercise increased the amplitude and reduced the time to 50% decay of Ca2+ transients. Exercise training increased the expression of miR-214 in hypertensive rats only.

Conclusion: The aerobic training applied in this study increased the availability of intracellular Ca2+ and accelerated the sequestration of these ions in left ventricular myocytes of hypertensive rats, despite increased expression of miR-214 and maintenance of cell contractility.

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Conflict of interest statement

Potential Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Figures

Figure 1
Figure 1
(A) Time to exhaustion of normotensive and hypertensive before (pre) and after (post) training. (B) Running velocity during training sessions. TN: trained normotensive; TH: trained hypertensive. Data are expressed as mean ± SD of 8 animals in each group. * compared with TN (pre); # compared with TH (pre) (p < 0.05).
Figure 2
Figure 2
Systolic arterial pressure (SAP) in normotensive animals and hypertensive animals. (A) SAP pre-training vs. post-training). (B) Final SAP of the groups. SN: sedentary normotensive; TN: trained normotensive; SH: sedentary hypertensive; TH: trained hypertensive. Data are expressed as mean ± SD of 8 animals in each group. * compared with TN (pre) (A) SN (B); & compared with TN (post) (A) TN (B); # compared with TH (pre) (A) SN (B); * compared with TH-post (A) TH (B) (p < 0.05).
Figure 3
Figure 3
Cardiomyocyte contractility in normotensive and hypertensive animals. (A) Contraction amplitude expressed as percentage of change in cell length at rest (%c.l.r.) after electrical stimulation at 1HZ; (B) time to peak concentration; (C) time to 50% of relaxation; SN, sedentary normotensive; TN, trained normotensive; SH, sedentary hypertensive; TH, trained hypertensive. Data as mean ± SD of 60-80 cells in each group. * compared with SN; # compared with SN; + compared with TH (p < 0.05).
Figure 4
Figure 4
Intracellular Ca2+ transient levels in cardiomyocytes of normotensive and hypertensive animals. (A) Amplitude of intracellular calcium. (B) Time to peak intracellular calcium. (C) Time to 50% decay of intracellular calcium. SN, sedentary normotensive; TN, trained normotensive; SH, sedentary hypertensive; TH, trained hypertensive. Data as mean ± SD of 40-50 cells in each group. * compared with SN; & compared with TN; # compared with SN; + compared with TH (p < 0.05).
Figure 5
Figure 5
MicroRNA-214 expression in the left ventricle in normotensive and hypertensive animals. SN: sedentary normotensive; TN: trained normotensive; SH: sedentary hypertensive; TH: trained hypertensive. Data as mean ± SD of 5 animals in each group. * compared with SN; & compared with TN; # compared with SN (p < 0.05).
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