QuestionSBA
QuestionChoice
This is incorrect. Phosphodiesterase inhibitors work by preventing cAMP and cGMP degradation, increasing their intracellular levels. This in turn increases the release of Ca2+ from the sarcoplasmic reticulum, increasing the contractility of the muscle cell.
10026309
e
Through inhibiting phosphodiesterases, they increase Ca2+ clearance from the cell
QuestionChoice
This is incorrect. Since phosphodiesterases degrade cAMP and cGMP, by inhibiting them, these drugs increase cAMP and cGMP levels. This then increases Ca2+ release from the sarcoplasmic reticulum.
10026306
b
Through inhibiting phosphodiesterases, they decrease the levels of cAMP and cGMP which increases Ca2+ release from the sarcoplasmic reticulum
QuestionChoice
This is correct. Phosphodiesterases (PDEs) breakdown the secondary messengers cAMP and cGMP. Phosphodiesterase inhibitors therefore work by preventing cAMP and cGMP degredation, increasing their intracellular levels. This in turn increases the release of Ca2+ from the sarcoplasmic reticulum, increasing the contractility of the muscle cell.
10026305
a
Through inhibiting phosphodiesterases, they increase the levels of cAMP and cGMP which increases Ca2+ release from the sarcoplasmic reticulum
QuestionChoice
This is incorrect. Phosphodiesterase inhibitors work by preventing cAMP and cGMP degradation, increasing their intracellular levels. This in turn increases the release of Ca2+ from the sarcoplasmic reticulum, increasing the contractility of the muscle cell.
10026308
d
Through inhibiting phosphodiesterases, they decrease intracellular Na+ which reduces the Na+/Ca2+ exchanger activity, increasing intracellular Ca2+
QuestionChoice
This is incorrect. This description is more similar to the mechanism of action of digoxin which blocks the Na+/K+ ATPase to increase intracellular Na+. Phosphodiesterase inhibitors work by preventing cAMP and cGMP degradation, increasing their intracellular levels. This in turn increases the release of Ca2+ from the sarcoplasmic reticulum, increasing the contractility of the muscle cell.
10026307
c
Through inhibiting phosphodiesterases, they increase intracellular Na+ which reduces the Na+/Ca2+ exchanger activity, increasing intracellular Ca2+
Concept
Chapter
2693
5887
Phosphodiesterase (PDE) enzymes and heart failure
Topic
169
Cardiovascular pharmacology
17659
Which of the following correctly describes the mechanism through which phosphodiesterase inhibitors act as inotropic drugs?
a