Renal outer medullary potassium (ROMK) channel is an important K⁺ excretion channel in the body, and K⁺ secreted by the ROMK channels is most or all source of urinary potassium. Previous studies focused on the ROMK channels of thick ascending limb (TAL) and collecting duct (CD), while there were few studies on the involvement of ROMK channels of the late distal convoluted tubule (DCT2) in K⁺ excretion. The purpose of the present study was mainly to record the ROMK channels current in renal DCT2 and observe the effect of high potassium diet on the ROMK channels by using single channel and whole-cell patch-clamp techniques. The results showed that a small conductance channel current with a conductance of 39 pS could be recorded in the apical membrane of renal DCT2, and it could be blocked by Tertiapin-Q (TPNQ), a ROMK channel inhibitor. The high potassium diet significantly increased the probability of ROMK channel current occurrence in the apical membrane of renal DCT2, and enhanced the activity of ROMK channel, compared to normal potassium diet (P < 0.01). Western blot results also demonstrated that the high potassium diet significantly up-regulated the protein expression levels of ROMK channels and epithelial sodium channel (ENaC), and down-regulated the protein expression level of Na⁺-Cl^- cotransporter (NCC). Moreover, the high potassium diet significantly increased urinary potassium excretion. These results suggest that the high potassium diet may activate the ROMK channels in the apical membrane of renal DCT2 and increase the urinary potassium excretion by up-regulating the expression of renal ROMK channels.
Potassium Channels, Inwardly Rectifying/metabolism* ; Kidney Tubules, Distal/metabolism* ; Potassium/metabolism* ; Epithelial Sodium Channels/metabolism* ; Diet

Virtually all of the dietary potassium intake is absorbed in the intestine, over 90% of which is excreted by the kidneys regarded as the most important organ of potassium excretion in the body. The renal excretion of potassium results primarily from the secretion of potassium by the principal cells in the aldosterone-sensitive distal nephron (ASDN), which is coupled to the reabsorption of Na⁺ by the epithelial Na⁺ channel (ENaC) located at the apical membrane of principal cells. When Na⁺ is transferred from the lumen into the cell by ENaC, the negativity in the lumen is relatively increased. K⁺ efflux, H⁺ efflux, and Cl^- influx are the 3 pathways that respond to Na⁺ influx, that is, all these 3 pathways are coupled to Na⁺ influx. In general, Na⁺ influx is equal to the sum of K⁺ efflux, H⁺ efflux, and Cl^- influx. Therefore, any alteration in Na⁺ influx, H⁺ efflux, or Cl^- influx can affect K⁺ efflux, thereby affecting the renal K⁺ excretion. Firstly, Na⁺ influx is affected by the expression level of ENaC, which is mainly regulated by the aldosterone-mineralocorticoid receptor (MR) pathway. ENaC gain-of-function mutations (Liddle syndrome, also known as pseudohyperaldosteronism), MR gain-of-function mutations (Geller syndrome), increased aldosterone levels (primary/secondary hyperaldosteronism), and increased cortisol (Cushing syndrome) or deoxycorticosterone (hypercortisolism) which also activate MR, can lead to up-regulation of ENaC expression, and increased Na⁺ reabsorption, K⁺ excretion, as well as H⁺ excretion, clinically manifested as hypertension, hypokalemia and alkalosis. Conversely, ENaC inactivating mutations (pseudohypoaldosteronism type 1b), MR inactivating mutations (pseudohypoaldosteronism type 1a), or decreased aldosterone levels (hypoaldosteronism) can cause decreased reabsorption of Na⁺ and decreased excretion of both K⁺ and H⁺, clinically manifested as hypotension, hyperkalemia, and acidosis. The ENaC inhibitors amiloride and Triamterene can cause manifestations resembling pseudohypoaldosteronism type 1b; MR antagonist spironolactone causes manifestations similar to pseudohypoaldosteronism type 1a. Secondly, Na⁺ influx is regulated by the distal delivery of water and sodium. Therefore, when loss-of-function mutations in Na⁺-K⁺-2Cl^- cotransporter (NKCC) expressed in the thick ascending limb of the loop and in Na⁺-Cl^- cotransporter (NCC) expressed in the distal convoluted tubule (Bartter syndrome and Gitelman syndrome, respectively) occur, the distal delivery of water and sodium increases, followed by an increase in the reabsorption of Na⁺ by ENaC at the collecting duct, as well as increased excretion of K⁺ and H⁺, clinically manifested as hypokalemia and alkalosis. Loop diuretics acting as NKCC inhibitors and thiazide diuretics acting as NCC inhibitors can cause manifestations resembling Bartter syndrome and Gitelman syndrome, respectively. Conversely, when the distal delivery of water and sodium is reduced (e.g., Gordon syndrome, also known as pseudohypoaldosteronism type 2), it is manifested as hypertension, hyperkalemia, and acidosis. Finally, when the distal delivery of non-chloride anions increases (e.g., proximal renal tubular acidosis and congenital chloride-losing diarrhea), the influx of Cl^- in the collecting duct decreases; or when the excretion of hydrogen ions by collecting duct intercalated cells is impaired (e.g., distal renal tubular acidosis), the efflux of H⁺ decreases. Both above conditions can lead to increased K⁺ secretion and hypokalemia. In this review, we focus on the regulatory mechanisms of renal potassium excretion and the corresponding diseases arising from dysregulation.
Humans ; Bartter Syndrome/metabolism* ; Pseudohypoaldosteronism/metabolism* ; Potassium/metabolism* ; Aldosterone/metabolism* ; Hypokalemia/metabolism* ; Gitelman Syndrome/metabolism* ; Hyperkalemia/metabolism* ; Clinical Relevance ; Epithelial Sodium Channels/metabolism* ; Kidney Tubules, Distal/metabolism* ; Sodium/metabolism* ; Hypertension ; Alkalosis/metabolism* ; Water/metabolism* ; Kidney/metabolism*

Humans ; Epilepsies, Myoclonic/diagnosis* ; NAV1.1 Voltage-Gated Sodium Channel

OBJECTIVE: To explore the genetic etiology of a patient with epilepsy and provide genetic counseling. METHODS: A patient who had visited the Center for Reproductive Medicine of Shandong University on November 11, 2020 was selected as the study subject, and her clinic information was collected. Candidate variant was identified through whole exome sequencing (WES), and Sanger sequencing was used for validation. Possible transcriptional changes caused by the variant was detected by reverse transcription-PCR and Sanger sequencing. RESULTS: The patient was a 35-year-old female with no fever at the onset, loss of consciousness and abnormal firing in the temporal lobe, manifesting predominantly as convulsions and fainting. WES revealed that she had harbored a heterozygous c.2841+5G>A variant of the SCN9A gene, which was verified by Sanger sequencing. cDNA sequencing confirmed that 154 bases were inserted between exons 16 and 17 of the SCN9A gene, which probably produced a truncated protein and affected the normal function of the SCN9A protein. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.2841+5G>A variant was classified as likely pathogenic (PVS1_Strong+PM2_Supporting). CONCLUSION The c.2841+5G>A variant of the SCN9A gene probably underlay the epilepsy in this patient. Above finding has enriched the variant spectrum of the SCN9A gene and provided a basis for the prenatal diagnosis and preimplantation genetic testing for this patient.
Humans ; Female ; Pregnancy ; Adult ; Epilepsy/genetics* ; Seizures ; Exons ; DNA, Complementary ; Genetic Counseling ; NAV1.7 Voltage-Gated Sodium Channel

Adenosine triphosphate (ATP) is well-known as a universal source of energy in living cells. Less known is that this molecule has a variety of important signaling functions: it activates a variety of specific metabotropic (P2Y) and ionotropic (P2X) receptors in neuronal and non-neuronal cell membranes. So, a wide variety of signaling functions well fits the ubiquitous presence of ATP in the tissues. Even more ubiquitous are protons. Apart from the unspecific interaction of protons with any protein, many physiological processes are affected by protons acting on specific ionotropic receptors-acid-sensing ion channels (ASICs). Both protons (acidification) and ATP are locally elevated in various pathological states. Using these fundamentally important molecules as agonists, ASICs and P2X receptors signal a variety of major brain pathologies. Here we briefly outline the physiological roles of ASICs and P2X receptors, focusing on the brain pathologies involving these receptors.
Humans ; Acid Sensing Ion Channels ; Protons ; Neurons ; Brain Diseases ; Adenosine Triphosphate/physiology*

Humans ; Myotonia Congenita/genetics* ; Mutation ; NAV1.4 Voltage-Gated Sodium Channel/genetics*

The East Asian scorpion Buthus martensii Karsch (BmK) is one of the classical traditional Chinese medicines for treating epilepsy for over a thousand years. Neurotoxins purified from BmK venom are considered as the main active ingredients, acting on membrane ion channels. Voltage-gated sodium channels (VGSCs) play a crucial role in the occurrence of epilepsy, which make them become important drug targets for epilepsy. Long chain toxins of BmK, composed of 60-70 amino acid residues, could specifically recognize VGSCs. Among them, α-like neurotoxins, binding to the receptor site-3 of VGSC, induce epilepsy in rodents and can be used to establish seizure models. The β or β-like neurotoxins, binding to the receptor site-4 of VGSC, have significant anticonvulsant effects in epileptic models. This review aims to illuminate the anticonvulsant/convulsant effects of BmK polypeptides by acting on VGSCs, and provide potential frameworks for the anti-epileptic drug-design.
Animals ; Anticonvulsants/therapeutic use* ; Neurotoxins/pharmacology* ; Scorpion Venoms/pharmacology* ; Scorpions/chemistry* ; Voltage-Gated Sodium Channels

Humans ; Mutation ; NAV1.5 Voltage-Gated Sodium Channel/genetics*

Objective: To summarize the genetics and clinical phenotypes of epilepsy children with 2q24.3 microdeletion. Methods: All the patients with 2q24.3 microdeletion were retrospectively collected at the Pediatric Department of Peking University First Hospital from March 2017 to July 2022. The features of clinical manifestations, electroencephalogram (EEG), and neuroimaging were analyzed. Results: There were 13 patients with 2q24.3 microdeletion were included. All 13 patients had de novo copy number variation (CNV) with a deletion size ranged 0.18-7.31 Mb. The main pathogenic genes in the region were SCN3A, SCN2A, TTC21B, SCN1A and SCN9A genes. Among the 13 patients, 7 were boys, and 6 were girls. The onset age of epilepsy was 3.3(2.5, 6.0) months. Multiple seizure types were observed, including focal seizures in 13 patients, generalized tonic-clonic seizures (GTCS) in 6 patients, myoclonic seizures in 3 patients, epileptic spasm in 2 patients, and tonic seizures in 2 patients. Seizures were fever sensitivity in 9 patients. Status epilepticus was observed in 6 patients. One case had normal mental motor development and 12 cases had different degrees of developmental delay. Six patients had craniofacial abnormality, 1 had six-finger deformity of the right thumb, and 1 had multiple system abnormalities. EEG showed focal discharge in 3 cases, multifocal discharges in 5 cases, multifocal and generalized discharges in 1 case. Brain magnetic resonance imaging (MRI) showed enlargement of subarachnoid spaces in the frontal and temporal region in 4 patients, enlargement of lateral ventricle in 4 patients and delayed myelination of white matter in 1 patient. Dravet syndrome was diagnosed in 5 cases. The age at the last follow-up were 2.5(1.4,5.5) years, 1 patient was seizure free longer than 1 year, and 12 patients still had seizures. Conclusions: The epilepsy associated with 2q24.3 microdeletion is mainly induced by the deletion of SCN3A, SCN2A and SCN1A genes. The seizure onset age of 2q24.3 microdeletion related epilepsy was in infancy. Multiple seizure types are observed and the common seizure types include focal seizures and GTCS. Most patients have fever sensitivity and status epilepticus. Most patients have developmental delay. The phenotype of patients with deletion of SCN3A and SCN2A gene is more severe than that of patients with deletion of SCN1A gene only.
Humans ; Abnormalities, Multiple ; Chromosomes ; DNA Copy Number Variations ; Epilepsies, Myoclonic ; Epilepsy ; Fever ; NAV1.7 Voltage-Gated Sodium Channel ; Phenotype ; Retrospective Studies ; Seizures ; Status Epilepticus ; Chromosomes, Human, Pair 2

Objective: Due to genetic factors might increase the risk of depression, this study investigated the genetic risk factors of depression in Chinese Han population by analyzing the association between 13 candidate genes and depression. Methods: 439 depression patients and 464 healthy controls were included in this case-control study. Case group consisted of 158 males and 281 females, aged (29.84±14.91) years old, who were hospitalized in three departments of the affiliated Brain Hospital of Guangzhou Medical University including Affective Disorders Department, Adult Psychiatry Department and Geriatrics Department, from February 2020 to September 2021. The control group consisted of 196 males and 268 females, aged (30.65±12.63) years old. 20 loci of 13 candidate genes in all subjects were detected by MALDI-TOF mass spectrometry. Age difference was compared using the student's t-test, the distributions of gender and genotype were analyzed with Pearson's Chi-square test. The analyses of Hardy-Weinberg equilibrium, allele frequency and the genetic association of depression were conducted using the corresponding programs in PLINK software. Results: PLINK analysis showed that SCN2A rs17183814, ABCB1 rs1045642, CYP2C19*3 rs4986893 and NAT2*5A rs1799929 were associated with depression before Bonferroni correction (χ²=10.340, P=0.001; χ²=11.010, P=0.001; χ²=9.781, P=0.002; χ²=4.481, P=0.034). The frequencies of minor alleles of above loci in the control group were 12.07%, 43.64%, 2.59% and 3.88%, respectively. The frequencies of minor alleles of loci mentioned above in the case group were 17.43%, 35.99%, 5.47% and 6.04%, respectively. OR values were 1.538, 0.726, 2.178 and 1.592, respectively. After 1 000 000 permutation tests using Max(T) permutation procedure, the four loci were still statistically significant, the empirical P-value were 0.002, 0.001, 0.003 and 0.042, respectively. However, only three loci including SCN2A rs17183814, ABCB1 rs1045642 and CYP2C19 rs4986893 had statistical significance after Bonferroni correction, the adjusted P-value were 0.026, 0.018 and 0.035, respectively. Conclusion: SCN2A rs17183814, ABCB1 rs1045642 and CYP2C19*3 rs4986893 were associated with depression's susceptibility in Chinese Han population. The A allele of SCN2A rs17183814 and CYP2C19*3 rs4986893 were risk factors for depression, while the T allele of ABCB1 rs1045642 was a protective factor for depression.
ATP Binding Cassette Transporter, Subfamily B/genetics* ; Adolescent ; Adult ; Alleles ; Arylamine N-Acetyltransferase/genetics* ; Case-Control Studies ; Clopidogrel ; Cytochrome P-450 CYP2C19/genetics* ; Depressive Disorder, Major/genetics* ; Female ; Gene Frequency ; Genetic Predisposition to Disease ; Genotype ; Humans ; Male ; NAV1.2 Voltage-Gated Sodium Channel ; Polymorphism, Single Nucleotide ; Young Adult