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Autoimmune conditions
Published in Ibrahim Natalwala, Ammar Natalwala, E Glucksman, MCQs in Neurology and Neurosurgery for Medical Students, 2022
Ibrahim Natalwala, Ammar Natalwala, E Glucksman
TRUE – The inability of the voltage-gated calcium ion channels to open means that insufficient quantities of acetylcholine are released into the synaptic cleft and therefore the postsynaptic membrane may not depolarise, thus causing muscle weakness. LEMS is particularly associated with small cell carcinoma of the lung.6
Neuronal Function
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Low plasma concentrations of calcium ions increase nerve (and muscle) excitability. This may appear contrary to the effects of low extracellular calcium on the Nernst potential, where the effect would be to hyperpolarize and reduce membrane excitability. The effects of low calcium ions are due to local charges on the membrane. There are fixed negative charges on membrane surfaces from polar phospholipids and proteins, which are normally balanced on the outside by positive calcium ions. These fixed charges usually have little effect on membrane potential as they are present on the inside and outside surfaces. A reduction in ionic plasma calcium produces an imbalance and allows the fixed negative charges on the outside of the cell to depolarize the membrane potential towards the threshold potential and increase cellular excitability and irritability.
Summation of Basic Endocrine Data
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
Sodium ion excretion is one of its major effects. It does not affect sodium transport mechanisms across cell membranes. It stimulates guanylase cyclase activity, particularly in kidney glomeruli. This enzyme helps form guanosine monophosphate (GMP), a second messenger that inhibits smooth muscle contraction. The inhibition involves changing the degree of phosphorylation of several enzymes. Intracellular calcium ion concentration is reduced.
Prokinetic effects of Citrus reticulata and Citrus aurantium extract with/without Bupleurum chinense using multistress-induced delayed gastric emptying models
Published in Pharmaceutical Biology, 2023
Yanrong Gong, Xiaoxia Liang, Yanting Dai, Xiang Huang, Qiaozhen Su, Yan Ma, Fenglian Chen, Shuling Wang
The GSMCs were successfully isolated and purified from rat stomach as observed under an inverted microscope (Figure 7(a)). The IFA with α-SMA as a specific marker depicted the characteristic of GSMCs and proved their authenticity in Figure 7(b). The viability of GSMCs after 5%, 10% and 20% medicated serums of AuCi and AuCiBup treatment for 12, 24, 36 or 48 h, respectively, was estimated with a CCK-8 kit to determine a medication dose and duration for the following intracellular Ca2+ assay. The unimpaired cell viability revealed 10% medicated serum treatment in 12 h was an optimal medication on GSMCs (Figure 8(a)). All 10% medicated serum treatment promoted calcium ion influx as displayed in Figure 8(b), whereas those of domperidone and AuCi enhanced 100% more fluorescence intensity and AuCiBup enhanced 200% than vehicle-treatment serum (p< 0.01, Figure 8(c)). Meanwhile, AuCiBup medicated serum significantly improved intracellular Ca2+ concentration in comparison with AuCi medicated serum (p< 0.05).
A pharmacovigilance analysis of FDA adverse event reporting system events for romosozumab
Published in Expert Opinion on Drug Safety, 2023
Zepeng Chen, Ming Li, Shuzhen Li, Yuxi Li, Junyan Wu, Kaifeng Qiu, Xiaoxia Yu, Lin Huang, Guanghui Chen
In addition, hypocalcemia, which may be related to the promotion of bone anabolism by romosozumab, is the result of the binding of calcium ions in the blood to bone. It has also been reported in previous articles that hypocalcemia will occur after the application of romosozumab [11,24]. This suggests that calcium supplementation may be necessary in the treatment of romosozumab. Compared with the adverse reactions in clinical trials, hyponatremia and hyperkalemia are newly found adverse reactions in our analysis results. These ion imbalances may also have a causal relationship with the impaired renal function caused by romosozumab. It is suggested that the adverse reactions of romosozumab should be given priority in the clinical application of these problems. In addition, it is necessary to pay close attention to the electrolyte balance in the body during the application, and adjust it in time when abnormal occurs.
Solanaceae glycoalkaloids: α-solanine and α-chaconine modify the cardioinhibitory activity of verapamil
Published in Pharmaceutical Biology, 2022
Szymon Chowański, Magdalena Winkiel, Monika Szymczak-Cendlak, Paweł Marciniak, Dominika Mańczak, Karolina Walkowiak-Nowicka, Marta Spochacz, Sabino A. Bufo, Laura Scrano, Zbigniew Adamski
Calcium ions are crucial for the contraction of all types of muscles. After influx into the cytoplasm, they interact with myofilaments and ultimately allow for interaction between myosin and actin filaments, and thus for muscle contraction. Since they are a trigger and an executor of muscle contractions, their concentration in the sarcoplasm must be strictly regulated. In striated muscles, cell membrane depolarization is a signal that initiates the cascade responsible for muscle contraction. Changes in the cell membrane potential activate and open the L-type calcium channels. Then, the local increase in Ca2+ concentration activates the ryanodine receptor, a sarcoplasmic calcium channel, which releases the next portion of calcium ions into the cytoplasm, which interacts with myofilaments.