26. Carbonic anhydrase is strongly inhibited by the drug acetazolamide, which is used as a diuretic and to lower excessively high pressure in the eye in glaucoma. Carbonic anhydrase plays an important role in these and other secretory processes because it participates in regulating the pH and bicarbonate content of several body fluids. The experimental curve of initial reaction velocity (as percentage of Vmax) versus (S] for the carbonic anhydrase reaction is illustrated below. When the experiment is repeated in the presence of acetazolamide, the lower curve is obtained. 100 No inhibiter 50 Acetazolamide 0.2 0.4 0.6 0.8 a. What happens to Vmas in the presence of the enzyme (E) and enzyme plus inhibitor (EI)? IS] (mM) b. What does the graph tell you about the ratios of Vmaxt/max(t)? c. What does the graph tell you about the concentration of (S] as the rate approaches Vmax with and without inhibitor? d. From an inspection of the curves and your knowledge of the kinetic properties of competitive, non- competitive and mixed non-competitive enzyme inhibitors what is the nature of the inhibition of acetazolamide? Explain. APSIA

26. Carbonic anhydrase is strongly inhibited by the drug acetazolamide, which is used as a diuretic and to lower excessively high pressure in the eye in glaucoma. Carbonic anhydrase plays an important role in these and other secretory processes because it participates in regulating the pH and bicarbonate content of several body fluids. The experimental curve of initial reaction velocity (as percentage of Vmax) versus (S] for the carbonic anhydrase reaction is illustrated below. When the experiment is repeated in the presence of acetazolamide, the lower curve is obtained. 100 No inhibiter 50 Acetazolamide 0.2 0.4 0.6 0.8 a. What happens to Vmas in the presence of the enzyme (E) and enzyme plus inhibitor (EI)? IS] (mM) b. What does the graph tell you about the ratios of Vmaxt/max(t)? c. What does the graph tell you about the concentration of (S] as the rate approaches Vmax with and without inhibitor? d. From an inspection of the curves and your knowledge of the kinetic properties of competitive, non- competitive and mixed non-competitive enzyme inhibitors what is the nature of the inhibition of acetazolamide? Explain. APSIA

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

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter15: Fluid And Acid-base Balance

Section: Chapter Questions

Problem 3SQE

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1. A woman who had been vomiting for 3 days was taken to the emergency department at University of Chicago by her family. The following blood measurements were obtained: pH = 7.6; PCO2 = 48 mmHg; and HCO3- = 37 mEq/L. A) Name the acid-base disorder you suspect that she has? And explain why you have selected this acid- base disorder. B) Provide a physiologic explanation for Gastrointestinal, Respiratory, and Renal changes that are taking place to either cause or compensate for the acid-base disorder.
Blood pH is maintained at a range of 7.4. The following set of equations representsthe reactions of the blood buffering system. The pk, for the dissociation ofH,COg into HOg and H* is 6.3.Carbonic AnhydraseCO2 + H2OH2CO3> HCO3- + H+(a) (Calculate the ratio [HCO3 ]/[H,COg] at physiological pH. Show work.(b)) An individual with diabetes presented at an urgent care with fatigue andnausea. Lab tests showed that their blood [HOg ]/[H,COg] ratio was 3.4. Whatwas the pH of the patient's blood? Show work.(c) ) Clinic staff also noticed that the patient was breathing rapidly. What isthe reason for this rapid breathing and how might it help alleviate the patient'scondition?
Harry ate a late meal at a cheap diner on the way home from work.A couple of hours later, he vomited three times, and then he consumed several packages of an antacid (mostly NaHCO3) over thenext several hours. By the evening of the next day, he was feelingbetter. During this ordeal, his blood pH did not deviate significantly.Select the mechanism(s) that helped maintain Harry’s pH within anormal range.(1) increased respiratory rate(2) increased H+ secretion by the renal tubule(3) decreased respiratory rate(4) decreased H+ secretion by the renal tubulea. 1 b. 2 c. 1,2 d. 3 e. 3,4
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