IJCS | Volume 33, Nº4, July and August 2020

325 Table 2 - Electrocardiographic parameters of hypertensive rats and its controls at six and 15 weeks of age Six weeks old 15 weeks old WIS L-NAME WKY SHR WIS L-NAME WKY SHR Heart rate (BPM) 478.4 ± 16.55 467.4 ± 34.70 462.8 ± 38.37 325.8 ± 74.09* # 427.4 ± 61.26 420.2 ± 31.12 426.7 ± 33.58 351.7 ± 94.33* RR interval (s) 0.1256 ± 0.0044 0.1291 ± 0.0101 0.1312 ± 0.0128 0.1916 ± 0.0378* # 0.1433 ± 0.0239 0.1445 ± 0.0118 0.1416 ± 0.0122 0.1831 ± 0.0508* # PR interval (s) 0.0507 ± 0.0051 0.0484 ± 0.0045 0.0463 ± 0.0017 # 0.0534 ± 0.0031* # 0.0495 ± 0.0031 0.0502 ± 0.0035 0.0484 ± 0.0034 0.0533 ± 0.0048* P duration (s) 0.0162 ± 0.0045 0.0137 ± 0.0041 0.0153 ± 0.0039 0.0256 ± 0.0088* # 0.0168 ± 0.0035 0.0159 ± 0.0044 0.0163 ± 0.0031 0.0202 ± 0.0047* QRS interval (s) 0.0119 ± 0.0032 0.0177 ± 0.0049 0.0199 ± 0.0058 # 0.0170 ± 0.0052 0.0144 ± 0.0030 0.0161 ± 0.0047 0.0162 ± 0.0062 0.0210 ± 0.0204 Qt interval (s) 0.0471 ± 0.0141 0.0530 ± 0.0146 0.0596 ± 0.0180 0.0394 ± 0.0070* # 0.0409 ± 0.0063 0.0569 ± 0.0149* 0.0524 ± 0.0139 # 0.0425 ± 0.0207 QTc (s) 0.1333 ± 0.0405 0.1484 ± 0.0438 0.1664 ± 0.0547 0.0909 ± 0.0154* # 0.1094 ± 0.0205 0.1495 ± 0.0383* 0.1398 ± 0.0373 0.1042 ± 0.0603 T peak T end Interval (s) 0.0123 ± 0.0057 0.0149 ± 0.0062 0.0122 ± 0.0058 0.0139 ± 0.0040 0.0135 ± 0.0050 0.0237 ± 0.0177 0.0159 ± 0.0093 0.0119 ± 0.0067 JT interval (s) 0.0341 ± 0.0127 0.0344 ± 0.0086 0.0351 ± 0.0124 0.0223 ± 0.0072 # 0.0250 ± 0.0089 0.0399 ± 0.0147* 0.0315 ± 0.0162 0.0197 ± 0.0070 # P amplitude (mV) 0.0376 ± 0.0046 0.0315 ± 0.0238 0.0448 ± 0.0220 0.0460 ± 0.0139 # 0.0261 ± 0.0153 0.0173 ± 0.0229 0.0309 ± 0.0188 0.0487 ± 0.0178* # Q amplitude (mV) 0 .0053 ± 0.0158 -0.0029 ± 0.0231 -0.0240 ± 0.0251 0.0023 ± 0.0105* -0 .0092 ± 0.0218 -0.0074 ± 0.0476 -0.0079 ± 0.0101 -0.0089 ± 0.0720 R amplitude (mV) 0.5448 ± 0.0828 0.5287 ± 0.1936 0.5883 ± 0.0970 0.4031 ± 0.2295* 0.4134 ± 0.1117 0.3163 ± 0.1301 0.4149 ± 0.0924 0.4884 ± 0.2930 S amplitude (mV) -0.1097 ± 0.1176 -0.1440 ± 0.1016 -0.1876 ± 0.1374 -0.0486 ± 0.0530* -0.0883 ± 0.1175 -0.1300 ± 0.1048 -0.1692 ± 0.0786 -0.0320 ± 0.1019* T amplitude (mV) 0.02443 ± 0.0481 0.0646 ± 0.0364 0.0243 ± 0.0264 0.0070 ± 0.0736 0.0104 ± 0.0502 0.0169 ± 0.0626 0.0105 ± 0.0234 -0.0310 ± 0.1202 ST Height -0.0131 ± 0.0317 0 .0094 ± 0.0329 -0.0267 ± 0.0074 -0.0412 ± 0.0343 -0.0156 ± 0.0380 -0.0202 ± 0.0224 -0.0387 ± 0.0237 -0.0468 ± 0.1094 First beat 1,251 ± 87.17 1,208 ± 72.64 1,172 ± 98.40 830.6 ± 178.1 1,097 ± 161.3 1,055 ± 97.52 1,082 ± 86.60 893.7 ± 246.8 Last beat 1,254 ± 87.17 1,211 ± 72.64 1,175 ± 98.40 833.6 ± 178.1 1,100 ± 161.3 1,058 ± 97.52 1,085 ± 86.60 896.7 ± 246.8 Electrocardiographic parameters of Wistar (WIS), Wistar-Kyoto (WKY), NG-monomethyl-L-arginine methyl ester (L-NAME)-induced hypertension, and spontaneously hypertensive rats (SHR) rats at six and 15 weeks of age. Data are presented as mean ± SD. *p < 0.05 compared to control (WIS vs. L-NAME; WKY vs. SHR); #p < 0.05 WIS vs. WKY; and L-NAME vs. SHR, n = 6. diastolic blood pressure in SHR compared with WKY at six weeks of life. 23 There are no data comparing ECG measures between WIS and WKY rats in the literature. SHR showed a decrease in HR when compared to WKYandL-NAME.Apossible interpretation of this data is the involvement of cyclic adenosine monophosphate (cAMP), which may be less available due to increased depletion induced by phosphodiesterase 3A (PDE3A). PDE3A is considered the main cAMP regulator in cardiomyocytes and an important regulator of cardiac contractility. 24-26 Increased expression of PDE3A results in reduced availability of cAMP and Grassi-Kassisse et al. ECG in hypertension models Int J Cardiovasc Sci. 2020; 33(4):321-328 Original Article