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Involvement of Epithelial Na + Channel in the Elevated Myogenic Response in Posterior Cerebral Arteries from Spontaneously Hypertensive Rats

View Article: PubMed Central - PubMed

ABSTRACT

Hypertension is characterized by increased peripheral vascular resistance which is related with elevated myogenic response. Recent findings have indicated that epithelial sodium channel (ENaC) is involved in mechanotransduction of the myogenic response. The purpose of this study was to investigate the involvement of ENaC in the elevated myogenic response of posterior cerebral arteries (PCAs) from spontaneously hypertensive rats (SHRs). Sixteen to eighteen weeks old male wistar kyoto rats (WKYs) and SHRs were used in this study. We found that wall to lumen (W/L) ratio was increased in the PCAs from SHRs compared with WKYs at the resting state. Interestingly, amiloride significantly inhibited myogenic response in the PCAs from SHRs and WKYs, however, the magnitude of the blockade was greater in SHRs. The transfection of γENaC-siRNA significantly reduced the expression of γENaC protein and inhibited myogenic response in the PCAs from SHRs. Furthermore, these data were supported by the findings that serum/glucocorticoid-induced kinase (Sgk1) and neural precursor cell-expressed developmentally downregulated gene 4-2 (Nedd4-2) were increased in SHRs compared with WKYs. Our results suggest that γENaC may play an important role in the elevated myogenic response in PCAs from SHRs.

No MeSH data available.


Related in: MedlinePlus

Comparison of amiloride effect on myogenic responses in the PCAs from SHRs and WKYs.(A and B) Representative recording showing the effect of 1 μmol/L amiloride on the myogenic response in the PCAs from WKYs and SHRs, respectively. (C) Mean data for the effect of amiloride. Data are expressed as means ± SEM and are normalized to myogenic tone at a diameter of 40 mmHg. *p < 0.05 for WKYs vs. WKYs with amiloride and $p < 0.005 for SHRs vs. SHRs with amiloride. (n = 12 in WKYs, n = 8 in WKYs with amiloride, n = 8 in SHRs, and n = 7 in SHRs with amiloride).
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f2: Comparison of amiloride effect on myogenic responses in the PCAs from SHRs and WKYs.(A and B) Representative recording showing the effect of 1 μmol/L amiloride on the myogenic response in the PCAs from WKYs and SHRs, respectively. (C) Mean data for the effect of amiloride. Data are expressed as means ± SEM and are normalized to myogenic tone at a diameter of 40 mmHg. *p < 0.05 for WKYs vs. WKYs with amiloride and $p < 0.005 for SHRs vs. SHRs with amiloride. (n = 12 in WKYs, n = 8 in WKYs with amiloride, n = 8 in SHRs, and n = 7 in SHRs with amiloride).

Mentions: To test whether ENaC proteins are required for the myogenic response and compare the difference in the contribution to the myogenic response between WKYs and SHRs, we evaluated myogenic responses in isolated PCAs from WKYs and SHRs in the presence of amiloride (1 μmol/L, specific ENaC blocker). Figure 2A and B show the typical traces indicating effects of ENaC blockade on the myogenic responses in the PCAs from WKYs and SHRs, respectively. The amiloride significantly inhibited myogenic response in both groups (Fig. 3C). Interestingly, the magnitude of blockade was greater in the PCAs from SHRs compared with the PCAs from WKYs.


Involvement of Epithelial Na + Channel in the Elevated Myogenic Response in Posterior Cerebral Arteries from Spontaneously Hypertensive Rats
Comparison of amiloride effect on myogenic responses in the PCAs from SHRs and WKYs.(A and B) Representative recording showing the effect of 1 μmol/L amiloride on the myogenic response in the PCAs from WKYs and SHRs, respectively. (C) Mean data for the effect of amiloride. Data are expressed as means ± SEM and are normalized to myogenic tone at a diameter of 40 mmHg. *p < 0.05 for WKYs vs. WKYs with amiloride and $p < 0.005 for SHRs vs. SHRs with amiloride. (n = 12 in WKYs, n = 8 in WKYs with amiloride, n = 8 in SHRs, and n = 7 in SHRs with amiloride).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382693&req=5

f2: Comparison of amiloride effect on myogenic responses in the PCAs from SHRs and WKYs.(A and B) Representative recording showing the effect of 1 μmol/L amiloride on the myogenic response in the PCAs from WKYs and SHRs, respectively. (C) Mean data for the effect of amiloride. Data are expressed as means ± SEM and are normalized to myogenic tone at a diameter of 40 mmHg. *p < 0.05 for WKYs vs. WKYs with amiloride and $p < 0.005 for SHRs vs. SHRs with amiloride. (n = 12 in WKYs, n = 8 in WKYs with amiloride, n = 8 in SHRs, and n = 7 in SHRs with amiloride).
Mentions: To test whether ENaC proteins are required for the myogenic response and compare the difference in the contribution to the myogenic response between WKYs and SHRs, we evaluated myogenic responses in isolated PCAs from WKYs and SHRs in the presence of amiloride (1 μmol/L, specific ENaC blocker). Figure 2A and B show the typical traces indicating effects of ENaC blockade on the myogenic responses in the PCAs from WKYs and SHRs, respectively. The amiloride significantly inhibited myogenic response in both groups (Fig. 3C). Interestingly, the magnitude of blockade was greater in the PCAs from SHRs compared with the PCAs from WKYs.

View Article: PubMed Central - PubMed

ABSTRACT

Hypertension is characterized by increased peripheral vascular resistance which is related with elevated myogenic response. Recent findings have indicated that epithelial sodium channel (ENaC) is involved in mechanotransduction of the myogenic response. The purpose of this study was to investigate the involvement of ENaC in the elevated myogenic response of posterior cerebral arteries (PCAs) from spontaneously hypertensive rats (SHRs). Sixteen to eighteen weeks old male wistar kyoto rats (WKYs) and SHRs were used in this study. We found that wall to lumen (W/L) ratio was increased in the PCAs from SHRs compared with WKYs at the resting state. Interestingly, amiloride significantly inhibited myogenic response in the PCAs from SHRs and WKYs, however, the magnitude of the blockade was greater in SHRs. The transfection of &gamma;ENaC-siRNA significantly reduced the expression of &gamma;ENaC protein and inhibited myogenic response in the PCAs from SHRs. Furthermore, these data were supported by the findings that serum/glucocorticoid-induced kinase (Sgk1) and neural precursor cell-expressed developmentally downregulated gene 4-2 (Nedd4-2) were increased in SHRs compared with WKYs. Our results suggest that &gamma;ENaC may play an important role in the elevated myogenic response in PCAs from SHRs.

No MeSH data available.


Related in: MedlinePlus