In this context, there is evidence of the genomic effects of TES on K+ channels in cardiomyocytes, where this hormone improved the expression of KV7.1 . Thus, it is conceivable that TES upregulates the expression of proteins involved in purinergic responses, including P2Y receptors and K+ channels. In addition, androgenic hormones enhance the relaxation of ASM caused by β adrenergic agonists 49,50, and TES induces ASM relaxation via an epithelial-dependent mechanism that is related to nitric oxide production .
Thus, we blocked the K+ channels with TEA, which reversed the effect of the androgen (Figure 1). In the experiments shown in the present work, a 48 h incubation of the androgen was performed, suggesting that the enhanced relaxation evoked by ATP and UTP may be due to a genomic pathway. On the other hand, we recently demonstrated the genomic effects of TES on ASM relaxation. Several studies have convincingly demonstrated the direct influence of TES on the relaxation of ASM. This shift indicates that ATP is enzymatically degraded under our experimental conditions. Our previous work has shown that blocking ectonucleotidases in guinea pig tracheal rings with ARL shifted the concentration–response curve to ATP to the left; i.e., the relaxation response was more intense .
The agonist of P2Y receptors, UTP, generates K+ currents that are amplified by testosterone (TES) via the androgen receptor signaling. To analyze the effects of TES and Flu appropriately, the increase in the K+ currents was compared concerning the tested concentration of ATP or UTP. Since K+ channels are implicated in the ATP and UTP relaxation responses , we conducted patch-clamp experiments to investigate whether TES could modify the K+ currents induced by these nucleotides. The effect of TES was abolished by the addition of TEA (1 mM), a nonspecific K+ channel blocker, suggesting that these channels are involved in the potentiation of smooth muscle relaxation. These results suggest that the androgen action involves the regulation of K+ channels, as the TES-induced enhancement of relaxation is abolished in the presence of TEA. We also explored other possible molecular mechanisms underlying the TES-induced enhancement of ATP- and UTP-evoked ASM relaxation, focusing on purinergic signaling pathways and regulation of KV channels.
As a matter of fact, according to the National Institutes of Health (NIH), testosterone can help improve muscle mass, bone density, mood, body composition, libido, and even cognition. Given the pre-existing smooth muscle contraction during asthma, ATP probably promotes relaxation. It is most likely that the increase in ATP- and UTP-induced K+ currents is exclusively due to the upregulation of K+ channels, specifically KV1.2 and KV1.5.
To find out which type of K+ channel is involved in the TES effect, we used blockers of the KV and the BKCa channels on the ATP- and UTP-induced K+ currents. (A) Depolarizing pulses ranging from −60 mV to +50 mV were applied to guinea pig tracheal myocytes. Testosterone (TES) enhances ATP-induced K+ currents through a genomic effect in guinea pig tracheal myocytes. Overall, these results confirm the genomic nature of the influence of TES on ATP- and UTP-induced K+ currents and the importance of P2Y receptors for generating K+ currents. Exposure of tracheal myocytes to TES 40 nM markedly increased the K+ currents generated by perfusion of ATP or UTP (Figure 2B and Figure 3B). The highest ATP concentration tested produced a K+ current of approximately 3.3 nA (Figure 2A,H), while UTP 1000 µM reached a peak of ~2 nA (Figure 3A,H). The maximum concentration of ATP used (1000 µM) in the presence of TES reached 89.15 ± 7.1% of relaxation, while UTP 1000 µM induced the relaxation of the tracheal tissues up to 53.21 ± 4.77% in the presence of the androgen.