We have located links that may give you full text access.
IN VITRO
JOURNAL ARTICLE
Time- and voltage-dependent block of the delayed K+ current by quinidine in rabbit sinoatrial and atrioventricular nodes.
Journal of Pharmacology and Experimental Therapeutics 1989 November
The modes in which quinidine blocks the delayed K+ current (IK) of rabbit sinoatrial and atrioventricular nodes were investigated by voltage clamp experiments using small preparations. Depolarizing pulses were applied from a holding potential of -50 mV and resultant IK current was evaluated. At a concentration of 2 x 10(-6) M, quinidine blocked 52 +/- 5% of IK with a 1000-msec test pulse of 0 mV, whereas it inhibited the slow inward current by only 5 to 10%. IK inhibition was enhanced with increasingly larger depolarizations. The activation curve obtained with the use of 1000-msec test pulses shifted toward hyperpolarization by 3.0 mV and its slope factor increased from 7.3 to 8.8, suggesting a voltage-dependent mechanism for IK blockage. Short and small depolarizing pulses from the holding potential of -50 mV hardly affected II. The activation of IK in the presence of quinidine did not show any delay. These results indicated a low affinity of quinidine to the closed (deactivated) channels. The deactivation time constant of IK was significantly prolonged from 120 to 145 msec at -50 mV. By applying the modulated receptor model to the K+ current, the tail current in the presence of quinidine was well reconstructed when the time constant of drug-channel interactions was 300 msec at -50 mV and 2000 msec at -30 mV. It is suggested that the unblocking of quinidine slows the decay of the IK tail current.
Full text links
Trending Papers
A Personalized Approach to the Management of Congestion in Acute Heart Failure.Heart International 2023
Potential Mechanisms of the Protective Effects of the Cardiometabolic Drugs Type-2 Sodium-Glucose Transporter Inhibitors and Glucagon-like Peptide-1 Receptor Agonists in Heart Failure.International Journal of Molecular Sciences 2024 Februrary 21
The Effect of Albumin Administration in Critically Ill Patients: A Retrospective Single-Center Analysis.Critical Care Medicine 2024 Februrary 8
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app