Piezo1 is a mechanosensitive non-selective cation channel. Genetic alterations of the channel result in a hematologic phenotype named Hereditary Xerocytosis. With Yoda1 and, more recently, Yoda2, compounds to increase the activity of Piezo1 have become available. However, their concrete effect depends on the nano environment of the channel and hence on the cell type. Here we compare the potency of Yoda1 and Yoda2 in red blood cells (RBCs). We investigate the effect of the compounds on direct channel activity using automated patch clamp, as well as the secondary effects of channel activation on signalling molecules and cellular response. In terms of signalling, we investigate the temporal response of the second messenger Ca²⁺, and in terms of cellular response, the activity of the Gárdos channel. The opening of the Gárdos channel leads to a hyperpolarisation of the RBCs, which is measured by the Macey–Bennekou–Egée (MBE) method. Although the interpretation of the data is not straightforward, we discuss the results in a physiological context and provide recommendations for the use of Yoda1 and Yoda2 to investigate RBCs.

Channelrhodopsins (ChRs) are light-gated ion channels originally discovered in algae and are commonly used in neuroscience for controlling the electrical activity of neurons with high precision. Initially-discovered ChRs were non-selective cation channels, allowing the flow of multiple ions, such as Na⁺, K⁺, H⁺, and Ca²⁺, leading to membrane depolarization and triggering action potentials in neurons. As the field of optogenetics has evolved, ChRs with more specific ion selectivity were discovered or engineered, offering more precise optogenetic manipulation. This review highlights the natural occurrence and engineered variants of sodium-selective channelrhodopsins (NaChRs), emphasizing their importance in optogenetic applications. These tools offer enhanced specificity in Na⁺ ion conduction, reducing unwanted effects from other ions, and generating strong depolarizing currents. Some of the NaChRs showed nearly no desensitization upon light illumination. These characteristics make them particularly useful for experiments requiring robust depolarization or direct Na⁺ ion manipulation. The review further discusses the molecular structure of these channels, recent advances in their development, and potential applications, including a proposed drug delivery system using NaChR-expressing red blood cells that could be triggered to release therapeutic agents upon light activation. This review concludes with a forward-looking perspective on expanding the use of NaChRs in both basic research and clinical settings.

Piezo1 is a mechanosensitive non-selective cation channel. Genetic alterations of the channel result in a hematologic phenotype named Hereditary Xerocytosis. With Yoda1 and more recently Yoda2, compounds to increase the activity of Piezo1 have become available. However, their concrete effect depends on the nano environment of the channel and hence on the cell type. Here we compare the potency of Yoda1 and Yoda2 in red blood cells (RBCs). We investigate the effect of the compounds on direct channel activity using automated patch clamp as well as the secondary effects of channel activation on signalling molecules and cellular response. In terms of signalling, we investigate the temporal response of the second messenger Ca2+, and in terms of cellular response, the activity of the Gárdos channel. The opening of the Gárdos channel leads to a hyperpolarisation of the RBCs, which is measured by the Macey-Bennekou-Egée (MBE) method. Although interpretation of the data is not straightforward, we discuss the results in a physiological context and provide recommendations for the use of Yoda1 and Yoda2 to investigate RBCs.