K R Courtney

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A new lidocaine derivative (Astra, GEA 968) depresses excitability of myelinated frog nerve in a manner which depends upon the rate of use of the nerve. This phenomenon has been shown, under voltage clamp conditions, to involve "frequency-" or "use-dependent" inhibition of the transient inward sodium currents at the node of Ranvier. With 0.6 mM GEA 968 in(More)
Different local anesthetic drug structures differ significantly in their capabilities for producing frequency (f)-dependent sodium channel block. Voltage-clamped frog myelinated nerve preparations have been utilized in order to investigate structure-activity relations for several modes of local anesthetic drug action, including the kinetics of f-dependent(More)
The Hodgkin-Huxley kinetic parameters, alpha h and beta h, which govern the rate of recovery from and development of sodium channel inactivation, respectively, have been measured as a function of membrane potential and external pH using a three-pulse protocol. alpha h but not beta h is substantially accelerated by reducing external pH from 7.4 to 6.4. The(More)
Excitable membranes exposed to sodium channel blocking agents (D; local anesthetics and antiarrhythmic drugs) show a progressive reduction of peak sodium current when repetitively depolarized (use dependence). Thus, with repetitive excitation, use dependence reflects a net rightward shift in the balance between unblocked channels (U) and blocked channels(More)
We have looked at several anticonvulsant drugs regarding their potency for basal block of sodium channels in both skeletal muscle and myelinated nerve preparations under voltage clamp conditions. There is an inverse relationship observed between the half-blocking concentration of each drug and its lipid distribution coefficient. Furthermore the(More)
It has been known for some time now that many antiarrhythmics and local anesthetics block sodium channels especially when they are depolarized. Two major phases of channel blocking occur, one "transient" and one "maintained" during the depolarization. Open channel blocking is thought to occur when intracellular forms of drug access the open channel via an(More)
Voltage clamp experiments were carried out on Rana catesbiana nodes of Ranvier in order to test predictions regarding the relationship between local anesthetic lipid solubility and the rate of development of and recovery from frequency-dependent increments of sodium channel block. Contrary to expectations, the drugs of greater lipid solubility than(More)
Single sodium channel openings have been recorded from cell-attached patches of isolated guinea pig ventricular myocytes. A paired pulse protocol was used to test the hypothesis that channel openings are required for lidocaine block. While the averaged ensemble current during the test pulse was much reduced, there was no correlation between the appearance(More)