The contraction of cardiac muscle cells results from the increase in Ca?+ levels in the cytosol. For these cells to relax, an antiport removes Ca?+ from the cytosol for every Na* that is taken in. Digitalis is a drug that is used to make the heart contract more strongly. This drug partially inhibits the Na*-K* ATPase in the cardiac cells. Applying the concepts from membrane transport, answer the following: a. Propose an explanation for the drug's effect. b. What will likely happen if too much of the drug is taken in? Why do you say so?

The contraction of cardiac muscle cells results from the increase in Ca?+ levels in the cytosol. For these cells to relax, an antiport removes Ca?+ from the cytosol for every Na* that is taken in. Digitalis is a drug that is used to make the heart contract more strongly. This drug partially inhibits the Na-K ATPase in the cardiac cells. Applying the concepts from membrane transport, answer the following: a. Propose an explanation for the drug's effect. b. What will likely happen if too much of the drug is taken in? Why do you say so?

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter7: The Peripheral Nervous System: Efferent Division

Section: Chapter Questions

Problem 1SQE

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The contraction of cardiac muscle cells results from the increase in calcium ion levels in the cytosol. For the cells to relax, an antiport removes calcium ion from the cytosol for every sodium ion that is taken in. Digitalis is a drug that is used to make the heart contract more strongly. This drug partially inhibits the Na+-K+ ATPase in the cardiac cells. Applying the concepts about membrane transport, answer the following: a. Propose an explanation for the drug’s effect.b. What will likely happen if too much of the drug is taken in? Why?
The sodium-calcium-exchanger (NCX) protein is an antiport protein that is located in the membranes of cardiac muscle cells in humans as well as other cells. Antiport proteins transport two different solutes in opposite directions. The sodium-calcium-exchanger protein functions by secondary active transport and requires the sodium-potassium pump in order to function. The sodium-potassium pump functions by primary active transport and transports sodium ions from the intracellular fluid to the extracellular fluid. • Describe how the sodium-potassium pump provides energy for the function of the sodium-calcium-exchanger. Considering that the NCX protein is an antiport protein, describe the concentration gradient of calcium on both sides of the cell membrane. Describe the direction that the calcium ions are transported.
Chloride ions (Cl-) behave a bit differently to Na+ and K+ in that most cells don't have active Cl- transporters. As a result, the concentration gradient for Cl- is not 'set' like it is for Na+ and K+. There are, however, a limited number of Cl- leak channels in the cell membrane. As a result, Eci generally matches resting membrane potential - around - 70mV. Considering this, answer the following questions. If Cl- can cross the cell membrane, is not being actively transported, and membrane potential is -70mV, will there be a concentration gradient for Cl-?
Usually , rates of diffusion vary inversely with molecular weights; so smaller molecules diffuse faster than do larger ones. In cells, however, calcium ion diffuses more slowly than does cAMP. Propose a possible explanation.
Some cells in the body express a Na+/K+/2Cl- cotransporter which pumps Cl- into the ICF. Where these pumps are present, the same GABA receptor is actually excitatory. Again, in the context of ECl describe how the same receptor would be excitatory in cells which actively pump Cl- into the ICF.
Here is a chloride cell in the gill epithelium of a fish. For reference, NKA = Na+/K+ ATPaseNKCC = Na+/K+/Cl- cotransporter. Given that the chloride cells of salt water fish have the NKCC transporter on the basal (bottom) side of the epithelium, what do you predict regarding the NKCC transporter in chloride cells of freshwater fish? A. The transporter must move chloride in the opposite direction, also from the bottom side of the cell. B. The NKCC transporter, as localized in salt water fish, could also work in freshwater fish. C. The transporter must move chloride in the opposite direction, but from the apical (top) side of the cell. D. A transporter is not needed to move Cl- ions into cells from fresh water.
Below find the structures for ibogaine and cocaine. Ibogaine and cocaine inhibit the dopamine active transporter (DAT). This transporter is a secondary active transporter, and depends on the primary active transporter Na+/K+ ATPase. Ibogaine had a Kι = 2 μM, and cocaine a Kι = 0.64 μM respectively. (a) Define secondary active transport. (b) Is ibogaine an effective treatment for cocaine based on DAT binding?
In cardiac muscle cells, the sodium-calcium exchanger maintains a low Ca²+ concentration in the cytoplasm. This antiporter works by exporting a single calcium ion for the import of three sodium ions. Find AG for the overall reaction.
Although purified actin can assemble reversibly in vitro, various actin-binding proteins regulate the assembly of actin filaments in the cell. Predict the effect on a cell’s actin cytoskeleton if function-blocking antibodies against each of the following were independently microinjected into cells: profilin, thymosin-β4, CapZ, and the Arp2/3 complex.
the sodium channel exchanger NCX transports sodium into and calcium out of cardiac muscle cells. Describe why this itransporter is classified as secondary active transport?
α-Bungarotoxin is a powerful neurotoxin found in the venom of a poisonous snake (Bungarus multicinctus). It binds with high specificity to the acetylcholine receptor (AChR; an integral membrane protein) andprevents its ion channel from opening. This interaction was used to purify AChR from the electric organ of torpedo fish.(a) Outline a strategy for using α-bungarotoxin covalently bound to chromatography beads to purify the AChR protein. (b) Outline a strategy for the use of [125I]α-bungarotoxin to purify the AChR protein.
Electrophoretic flow and electroosmotic flow (EOF) plays an important role in capillary electrophoresis (CE) for ions movement. Explain the differences between electrophoretic flow and EOF. b) Suggest two different approaches (other than reducing the voltage) to reduce the electroosmotic flow. c) Three water soluble vitamins: niacinamide (a neutral compound), riboflavin (a neutral compound) and thiamine (a cation) were separated by micellar electrokinetic capillary chromatography (MEKC) in 15 mM borate buffer (pH 8) with 50 mM sodium dodecyl sulfate. The migration times were niacinamide (7.5 min), riboflavin (12.8 min) and thiamine (13.9 min) Explain why these vitamins were separated using MEKC. Explain why niacinamide and riboflavin (both are neutral compounds) have different migration times. (i) With the aid of a diagram, differentiate flow profile of electroosmotic flow (EOF) and laminar flow. (ii) Discuss the effect of both flows in term of peak resolution.