Biomaterial Database

Electrophysiological effects of tetracaine in single guinea-pig ventricular myocytes. 1986

E Carmeliet, and M Morad, and G Van der Heyden, and J Vereecke

The effect of tetracaine on the ionic current in enzymatically dissociated single guinea-pig ventricular cells was studied using a two micro-electrode voltage-clamp technique. The myocytes were pre-incubated with Cs+ and the experiments were performed at room temperature in order to reduce the contribution of the delayed outward current. Tetracaine decreased the maximum rate of rise of the action potential with a dissociation constant (KD) strongly dependent on the holding potential (0.77 microM at -80 mV, and 6.2 microM at -95 mV). Application of 20 microM-tetracaine resulted in about a 50% reduction of the inwardly rectifying K+ current, while ten times higher concentrations were required to suppress the delayed K+ current. The inactivation time course of the Ca2+ current could be fitted with two exponentials, with time constants tau f = 15 ms and tau s = 150 ms at around 0 mV. Tetracaine decreased the amplitude of the Ca2+ current and speeded its decay. This effect was found to be primarily due to a marked inhibition of the amplitude of the slowly inactivating component (apparent KD = 80 microM, nH = 2). The drug had little effect on the time constants of the two components of Ca2+ channel inactivation. When Sr2+ or Ba2+ were the charge carriers, inactivation of the Ca2+ channel was again fitted with a fast and a slow exponential. In addition, a maintained (or very slowly inactivating) component was present. Tetracaine not only suppressed the amplitudes of the slowly inactivating and the maintained components, but also decreased the time constant of the slowly inactivating component. The results are consistent with a direct effect of tetracaine on the high threshold Ca2+ channel and do not support indirect effects of the drug secondary to suppression of Ca2+ release from internal stores.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001464	Barium	An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.