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Pain by chemical irritants is one of the less well-described aspects of nociception. The acidic substance is the paradigm of the chemical noxious compound. An acidic insult on cutaneous, subcutaneous and muscle tissue results in pain sensation. Acid (or H+) has at least two main receptor channels in dorsal root ganglia (DRG) nociceptors: the heat receptor transient receptor potential vanilloid 1 (TRPV1) and the acid-sensing ionic channels (ASICs). TRPV1 is a low-sensitivity H+ receptor, whereas ASIC channels display a higher H+ sensitivity of at least one order of magnitude. In this review, we first describe the functional and structural characteristics of these and other H+-receptor candidates and the biophysics of their responses to low pH. Additionally, we compile reports of the expression of these H+-receptors (and other possible complementary proteins) within the DRG and compare these data with mRNA expression profiles from single-cell sequencing datasets for ASIC3, ASIC1, transient receptor potential Ankiryn subtype 1 (TRPA1) and TRPV1. We show that few nociceptor subpopulations (discriminated by unbiased classifications) combine acid-sensitive channels. This comparative review is presented in light of the accumulating evidence for labeled-line coding for most noxious sensory stimuli. [ABSTRACT FROM AUTHOR]

Ca2+ currents (ICa) recorded from adrenal chromaffin cells (CCs) of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats are similar to one another, but different from those recorded in other rodent species. ICa in WKY/SHR CCs comprises an early, transient (ICae) and a late, sustained component (ICas). In Wistar CCs, ICae is absent, and ICas is of greater amplitude. Activation and steady-state inactivation of ICa and ICa in WKY/SHR CCs suggest the recruitment of at least two populations of Ca2+ channels with different voltage dependence and kinetics. In WKY/SHR CCs, ICa is inhibited by nifedipine, enhanced by BAY K 8644, is not blocked by the mibefradil analog NNC 55-0396, and displays Ca2+ dependent inactivation and fast deactivation kinetics, suggesting that it results from the opening of L-type rather than T-type Ca2+ channels. ICae properties suggest that it originates from the opening of Ca2+ channels formed with the short splice variant (CaV1.342A). RTPCR showed that expression of CaV1.342A mRNA is similar in both Wistar and WKY/SHR, but that the long variant (CaV1.342) is virtually absent in WKY/SHR. Thus ICae corresponds to the recruitment of CaV1.342A channels, unmasked by the absence of CaV1.342 channels. Studies in WKY CCs do not report major functional alterations, despite the unusual expression pattern of CaV1.3 splice variants. It remains to be established if more subtle functional alterations exist, and if the atypical splicing pattern of CaV1.3 could be related to the functional and behavioral alterations reported in WKY/SHR rats, including their susceptibility to develop hypertension. [ABSTRACT FROM AUTHOR]

The spontaneously hypertensive rat (SHR) is a model widely used to investigate the causal mechanisms of essential hypertension. The enhanced catecholamine (CA) release reported in adrenal glands from adult SHRs raised considerable interest for its possible implication in the genesis of hypertension. The use of powerful techniques such as calcium imaging, electrophysiology, and single-cell amperometry to monitor in real time the key steps in CA secretion has allowed a better understanding of the role of chromaffin cells (CC) in the pathophysiology of hypertension, although several questions remain. Additionally, the implementation of these techniques in preparations in situ, such as the acute adrenal gland slice, which maintains the microenvironment, cell-to-cell communication, and anatomical structure similar to that of the intact adrenal gland, yields data that may have even greater physiological relevance. Here, we describe the procedures to measure the blood pressure of rats in a noninvasive manner, how to obtain primary cultures of adrenal chromaffin cells and acute adrenal slices, and how to perform amperometric recordings and intracellular calcium imaging in these preparations., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Pain by chemical irritants is one of the less well-described aspects of nociception. The acidic substance is the paradigm of the chemical noxious compound. An acidic insult on cutaneous, subcutaneous and muscle tissue results in pain sensation. Acid (or H + ) has at least two main receptor channels in dorsal root ganglia (DRG) nociceptors: the heat receptor transient receptor potential vanilloid 1 (TRPV1) and the acid-sensing ionic channels (ASICs). TRPV1 is a low-sensitivity H + receptor, whereas ASIC channels display a higher H + sensitivity of at least one order of magnitude. In this review, we first describe the functional and structural characteristics of these and other H + -receptor candidates and the biophysics of their responses to low pH. Additionally, we compile reports of the expression of these H + -receptors (and other possible complementary proteins) within the DRG and compare these data with mRNA expression profiles from single-cell sequencing datasets for ASIC3, ASIC1, transient receptor potential Ankiryn subtype 1 (TRPA1) and TRPV1. We show that few nociceptor subpopulations (discriminated by unbiased classifications) combine acid-sensitive channels. This comparative review is presented in light of the accumulating evidence for labeled-line coding for most noxious sensory stimuli., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Páez, Segura-Chama, Almanza, Pellicer and Mercado.)

Automated technologies are now resolving the historical relegation that ion channels have endured as targets for the new drug discovery and development global efforts. The richness and adequacy of functional assay methodologies, remarkably fluorescence-based detection of ions fluxes and patch-clamp electrophysiology recording of ionic currents, are now automated and increasingly employed for the analysis of ion channel activity. While the former is currently the most commonly applied, the latter is finally reaching the throughput capacity to be engaged in the primary screening of chemical libraries conformed by hundreds of thousands of compounds. The use of automated instrumentation for the study of ion channel functionality (and dysfunctionality), particularly in the search for novel pharmacological agents with therapeutic purposes, has now reached out beyond the industrial setting, its original natural enclave, and is making its way into a growing number of academic labs and core facilities. The present chapter reviews the increasing contributions accomplished by a variety of different key automated technologies which have revolutionized the strategies to approach the discovery and development of new drugs targeting ion channels., (© 2016 Elsevier Inc. All rights reserved.)

Ca(2+) currents (I(Ca)) recorded from adrenal chromaffin cells (CCs) of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats are similar to one another, but different from those recorded in other rodent species. I(Ca) in WKY/SHR CCs comprises an early, transient (I(Ca(e))) and a late, sustained component (I(Ca(s))). In Wistar CCs, I(Ca(e)) is absent, and I(Ca(s)) is of greater amplitude. Activation and steady-state inactivation of I(Ca(e)) and I(Ca(s)) in WKY/SHR CCs suggest the recruitment of at least two populations of Ca(2+) channels with different voltage dependence and kinetics. In WKY/SHR CCs, I(Ca(e)) is inhibited by nifedipine, enhanced by BAY K 8644, is not blocked by the mibefradil analog NNC 55-0396, and displays Ca(2+)-dependent inactivation and fast deactivation kinetics, suggesting that it results from the opening of L-type rather than T-type Ca(2+) channels. I(Ca(e)) properties suggest that it originates from the opening of Ca(2+) channels formed with the short splice variant (Ca(V)1.3(42A)). RT-PCR showed that expression of Ca(V)1.3(42A) mRNA is similar in both Wistar and WKY/SHR, but that the long variant (Ca(V)1.3(42)) is virtually absent in WKY/SHR. Thus I(Ca(e)) corresponds to the recruitment of Ca(V)1.3(42A) channels, unmasked by the absence of Ca(V)1.3(42) channels. Studies in WKY CCs do not report major functional alterations, despite the unusual expression pattern of Ca(V)1.3 splice variants. It remains to be established if more subtle functional alterations exist, and if the atypical splicing pattern of Ca(V)1.3 could be related to the functional and behavioral alterations reported in WKY/SHR rats, including their susceptibility to develop hypertension.