We studied the influence of Mn, La, and D600 on action potentials and plateau currents in cardiac Purkinje fibers. The Ca antagonists each abolished the second inward current, but they failed to act selectively. Voltage clamp experiments revealed two additional effects: decrease of slow outward current (iotachi) activation, and increase of net outward time-independent plateau current. These effects occurred at inhibitor concentrations used in earlier studies, and were essential to the reconstruction of observed Ca antagonist effects on electrical activity. The inhibitory influence of Mn, La, and D600 on iotachi suggested that iotachi activation might depend upon prior Ca entry. This hypothesis was not supported, however, when [Ca]omicron was varied: elevating [Ca]omicron enhanced Ca entry, but iotachi was nevertheless depressed. Thus, the results suggested instead that Ca antagonists and Ca ions have rather similar effects on iotachi, possibly mediated by changes in membrane surface charge.
Skip Nav Destination
Article navigation
1 August 1975
Article|
August 01 1975
Multiple effects of calcium antagonists on plateau currents in cardiac Purkinje fibers.
R S Kass
R W Tsien
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1975) 66 (2): 169–192.
Citation
R S Kass, R W Tsien; Multiple effects of calcium antagonists on plateau currents in cardiac Purkinje fibers.. J Gen Physiol 1 August 1975; 66 (2): 169–192. doi: https://doi.org/10.1085/jgp.66.2.169
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Calcium- and voltage-activated plateau currents of cardiac Purkinje fibers.
J Gen Physiol (June,1987)
4-Aminopyridine and the early outward current of sheep cardiac Purkinje fibers.
J Gen Physiol (February,1979)
Control of action potential duration by calcium ions in cardiac Purkinje fibers.
J Gen Physiol (May,1976)
Email alerts
Advertisement