Kinins

Question 1

Kinins are potent vasodilator peptides formed enzymatically by the action of enzymes known as ____(a)____ or ____(b)____ acting on protein substrates called ____(c)____.

Answer 1

(a) kallikreins, (b) kininogenases, (c) kininogens

Question 2

Name two kinins.

Answer 2

(1) Bradykinin
(2) Kallidin

Question 3

List physiological effects of kinins.

Answer 3

(1) Vasodilation; relaxation of vascular smooth muscles, leading to the widening of blood vessels and a decrease in blood pressure.
(2) Increased vascular permeability: Kinins enhance the permeability of blood vessels, allowing proteins and fluids to leak into the surrounding tissues, which can contribute to inflammation and edema.
(3) Pain stimulation: Kinins activate sensory nerve endings, leading to the sensation of pain. This is particularly relevant in inflammatory conditions.
(4) Contraction of smooth muscles: Kinins can cause the contraction of non-vascular smooth muscles, such as those in the gastrointestinal and respiratory tracts.
(5) Increased bronchial secretion: Kinins stimulate the secretion of mucus in the airways, which can affect respiratory function.
(6) Activation of the inflammatory response: Kinins play a role in the activation and regulation of the inflammatory response, attracting immune cells to sites of tissue injury or infection.

Question 4

Explain the relationship between kinins and hereditary angioedema.

Answer 4

◾ HA is a rare autosomal dominant disorder that results from deficiency or dysfunction of the C1 esterase inhibitor (C1-INH).
◾ This protein regulates the complement system and other pathways, including the kallikrein-kinin system.
◾ C1-INH deficiency results in activation of kallikrein and increased formation of bradykinin.
◾ Bradykinin increases vascular permeability and also leads to recurrent episodes of angioedema of the airways, GIT, extremeties, and genitalia, which can be debilitating.

Question 5

types of kinin receptors

Answer 5

B₁ and B₂

Question 6

What type of receptors are kinin receptors?

Answer 6

GPCRs

Question 7

Compare B₁ and B₂ kinin receptors in terms of expression.

Answer 7

B₁ receptors: These are not typically expressed in most normal tissues. Their expression is induced by tissue injury, inflammation, or other pathological conditions.

B₂ receptors: These are constitutively expressed throughout the body and are present in various tissues under normal physiological conditions.

Question 8

Icatibant mode of action and administration

Answer 8

MOA: B₂ receptor antagonist; receptor affinity similar to that of bradykinin
Administration: subcutaneous

Question 9

3 kallikrein inhibitors

Answer 9

(1) Aprotinin
(2) Ecallantide
(3) Lanadelumab

Question 10

Which drug enhances the effects of kinins?
(a) Ecallantide
(b) Cinryze
(c) Berinert
(d) Captopril
(e) Aprotinin

Answer 10

(d) Captopril

Question 11

Which drug enhances the effects of kinin:
(a) lcatibant
(b) Aspirin
(c) Aprotinin
(d) Berinert
(e) Enalapril

Answer 11

(e) Enalapril

Question 12

Pharmacological actions of bradykinin include the following except ________.
(a) vasoconstriction
(b) increased vascular permeability
(c) stimulation of pain nerve endings
(d) increased bronchial secretion
(e) diarrhoea

Answer 12

(a) vasoconstriction

Question 13

Choose the group of antihypertensive drugs which diminishes the metabolism of bradykinin:
(a) Ganglioblockers
(b) Alfa-adrenoblockers
(c) Angiotensin-converting enzyme inhibitors
(d) Diuretics

Answer 13

(c) Angiotensin-converting enzyme inhibitors

Question 14

Which of the following is not true of ecallantide?
(a) Is a recombinant plasma kallikrein inhibitor.
(b) Is administered intravenously.
(c) May cause anaphylaxis.
(d) Is more potent than cinryze.
(e) Is used for treatment of acute episodes of hereditary angioedema.

Answer 14

(b) Is administered intravenously.

Question 15

C1 esterase inhibitors (C1-INH)

Answer 15

cinryze, berinert