Exploring new horizons: angiotensin II, angiotensin II type 1 receptor, and renal outer medullary potassium channel interaction in distal convoluted tubule

Figures

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  Figure 1.. Effect of Ang II on ROMK channel activity and protein expression in the lumen membrane of DCT2 in a low potassium diet. (A) Single-channel patch clamp technique was used to detect the ROMK channel activity in the lumen membrane of DCT2 in each group. The representative traces of ROMK channel activity induced by 100 nM Ang II in normal and low potassium diets are shown in the left and middle panels. The closed state of the channel (“C”) is represented by a dashed line. The current ROMK channel activity is indicated by the short bar on the right side of each trace. The dose-response curve of Ang II on ROMK channel activity in the lumen membrane of DCT2 induced by normal and low potassium diets is shown in the right panel. (B) Whole-cell patch clamp technique was used to measure the tertiapin-Q (TPNQ)-sensitive K+ current and voltage stimulation protocol in the lumen membrane of DCT2 in each group. (C) Statistical analysis of the TPNQ-sensitive K+ current in the lumen membrane of DCT2 in each group measured by the whole-cell patch clamp technique. (D) Western blot analysis of ROMK protein expression in the lumen membrane of DCT2 in each group. (E) Immunofluorescence detection of…

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  Figure 2.. Ang II-mediated regulation of ROMK channel activity in the lumen membrane of DCT2 via AT1R receptor. (A) Single-channel patch clamp technique was used to examine the effect of AT1R antagonist losartan in combination with Ang II on ROMK channel activity in the lumen membrane of DCT2. The closed state of the channel (“C”) is represented by a dashed line. The current ROMK channel activity is indicated by the short bar on the right side of each trace. (B) Single-channel patch clamp technique was used to examine the effect of AT2R antagonist PD123319 in combination with Ang II on ROMK channel activity in the lumen membrane of DCT2. 1–3 indicate ROMK channel activity measured at different time points. The closed state of the channel (“C”) is represented by a dashed line. The current ROMK channel activity is indicated by the short bar on the right side of each trace. (C) Measurement of the strength of tertiapin-Q (TPNQ)-sensitive K+ current in the lumen membrane of DCT2 in each group treated with AT1R antagonist losartan in combination with Ang II, with the left panel showing the current changes and the right panel showing the statistical analysis. (D) Measurement of the strength of…

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  Figure 3.. Identification of key pathways for Ang II-induced hypertension by transcriptome sequencing. (A) Heatmap of differentially expressed genes in the control group and the Ang II-treated group, with red indicating upregulation and blue indicating downregulation. Group 1 represents the control group, and group 2 represents the Ang II-treated group. (B) Gene Ontology enrichment analysis results of differentially expressed genes, with larger circles indicating more enrichment and bluer colors indicating more significant p-values. (C) Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis results of differentially expressed genes, with larger circles indicating more enrichment and bluer colors indicating more significant p-values. (D) Western blot analysis of p-JAK2 and JAK2 protein expression in the lumen membrane of distal convoluted tubule 2 in each group. Ang II, angiotensin II; ARVC, arrhythmogenic right ventricular cardiomyopathy; cAMP, cyclic adenosine monophosphate; ECM, extracellular matrix; JAK2, janus kinase 2; LK, low potassium; NK, normal potassium; PPAR, peroxisome proliferator-activated receptor; STAT, signal transducer and activator of transcription. ***p <…

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  Figure 4.. Suppression of ROMK channel activity in the lumen membrane of DCT2 by activation of JAK2 signaling pathway in a low potassium Diet. (A) Single-channel patch clamp technique was used to examine the effect of JAK2 inhibitor AG490 on ROMK channel activity in the lumen membrane of DCT2. indicate ROMK channel activity measured at different time points. The closed state of the channel (“C”) is represented by a dashed line. The current ROMK channel activity is indicated by the short bar on the right side of each trace. (B) Measurement of the strength of tertiapin-Q (TPNQ)-sensitive K+ current in the lumen membrane of DCT2 treated with JAK2 inhibitor AG490, with the left panel showing the current changes and the right panel showing the statistical analysis. (C) Effect of JAK2 inhibitor AG490 on ROMK, p-JAK2, and JAK2 protein expression in the lumen membrane of DCT2 as detected by Western blotting. DCT, distal convoluted tubule; JAK2, janus kinase 2; LK, low potassium; NPo, number of channels × probability of openness; ROMK, renal outer medullary potassium channel. ***p < 0.001, significantly different between the two groups; n = 10.

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  Figure 5.. Ang II inhibits ROMK channel activity in the lumen of the DCT2 membrane by mediating the JAK2 signaling pathway in a low potassium diet. (A) The effect of AG490 and Ang II combined on ROMK channel activity in the lumen of the DCT2 membrane was detected using the patch clamp technique. The closed state of the channel (“C”) is indicated by a dashed line. The current ROMK channel activity is represented by the short bar on the right side of each trace. (B) The effect of AG490 and Ang II combined on the intensity of tertiapin-Q (TPNQ)-sensitive K+ currents in the lumen of the DCT2 membrane was measured using the whole-cell patch clamp technique. The left graph shows the recording of current changes, and the right graph shows the statistical representation. (C) The effect of AG490 and Ang II combined on the expression of ROMK, p-JAK2, and JAK2 proteins in the lumen of the DCT2 membrane was detected using Western blot. Ang II, angiotensin II; DCT, distal convoluted tubule; JAK2, janus kinase 2; LK, low potassium; NPo, number of channels × probability of openness; ROMK, renal outer medullary potassium channel. ***p < 0.001, significantly different between the two groups; n = 10.

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  Figure 6.. Ang II inhibits ROMK channel activity mediated by the AT1R/JAK2 signaling pathway. (A) The effect of AG490 and Ang II combined on the expression of AT1R and p-JAK2 proteins in mouse renal cortex tissue was detected using immunohistochemistry. (B) The effect of AG490 and Ang II combined on the expression of ROMK, AT1R, p-JAK2, and JAK2 proteins in mouse renal cortex tissue was detected using Western blot. (C) The effect of AG490 and Ang II combined on ROMK channel activity in the lumen of mouse distal convoluted tubule (DCT) 2 membrane was detected using the patch clamp technique. The ROMK channel activities detected at different time points are labeled as 1–3. The closed state of the channel (“C”) is indicated by a dashed line. The current ROMK channel activity is represented by the short bar on the right side of each trace. (D) The effect of AG490 and Ang II combined on the intensity of tertiapin-Q (TPNQ)-sensitive K+ currents in the lumen of mouse DCT2 membrane was measured using the whole-cell patch clamp technique. The left graph shows the recording of current changes, and the right graph shows the statistical representation. (E) The urinary potassium excretion in the…

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  Figure 7.. Molecular mechanism diagram showing that Ang II inhibits the activity of ROMK in the DCT during a low potassium diet via activation of the JAK2 pathway through AT1R. Ang II, angiotensin II; AT1R, Ang II type 1 receptor; DCT, distal convoluted tubule; JAK2, janus kinase 2; ROMK, renal outer medullary potassium channel.

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