Investigating the Impact of Selective Modulators on the Renin–Angiotensin–Aldosterone System: Unraveling Their Off-Target Perturbations of Transmembrane Ionic Currents

The renin–angiotensin–aldosterone system (RAAS) plays a crucial role in maintaining various physiological processes in the body, including blood pressure regulation, electrolyte balance, and overall cardiovascular health. However, any compounds or drugs known to perturb the RAAS might have an additional impact on transmembrane ionic currents. In this retrospective review article, we aimed to present a selection of chemical compounds or medications that have long been recognized as interfering with the RAAS. It is noteworthy that these substances may also exhibit regulatory effects in different types of ionic currents. Apocynin, known to attenuate the angiotensin II-induced activation of epithelial Na(+) channels, was shown to stimulate peak and late components of voltage-gated Na(+) current (I(Na)). Esaxerenone, an antagonist of the mineralocorticoid receptor, can exert an inhibitory effect on peak and late I(Na) directly. Dexamethasone, a synthetic glucocorticoid, can directly enhance the open probability of large-conductance Ca(2+)-activated K(+) channels. Sparsentan, a dual-acting antagonist of the angiotensin II receptor and endothelin type A receptors, was found to suppress the amplitude of peak and late I(Na) effectively. However, telmisartan, a blocker of the angiotensin II receptor, was effective in stimulating the peak and late I(Na) along with a slowing of the inactivation time course of the current. However, telmisartan’s presence can also suppress the erg-mediated K(+) current. Moreover, tolvaptan, recognized as an aquaretic agent that can block the vasopressin receptor, was noted to suppress the amplitude of the delayed-rectifier K(+) current and the M-type K(+) current directly. The above results indicate that these substances not only have an interference effect on the RAAS but also exert regulatory effects on different types of ionic currents. Therefore, to determine their mechanisms of action, it is necessary to gain a deeper understanding.