Biomaterial Database

Effect of halothane on large-conductance calcium-dependent potassium channels in cerebrovascular smooth muscle cells of the rat. 1994

Y Hong, and E Puil, and D A Mathers

Department of Physiology, Faculty of Medicine, University of British Columbia, Vancouver, Canada.

BACKGROUND Patch-clamp methods were used to examine the effects of the volatile general anesthetic halothane on large-conductance calcium-dependent potassium channels (BK channels) in dispersed cerebrovascular smooth muscle cells of adult rats. METHODS Inside-out membrane patches were used for recordings at 21-23 degrees C. Halothane was administered at aqueous concentrations of 0.5-2.8 mM in conjunction with free cytoplasmic calcium concentrations of 1 or 100 microM and at a membrane potential of -60 mV or +60 mV. RESULTS At a free cytoplasmic calcium concentration of 1 microM, the clinically relevant dose of 0.5 mM (2 MAC) halothane reduced the open probability of large-conductance calcium-dependent potassium channels without altering the single-channel conductance. This effect was blocked by increasing the concentration of cytoplasmic free calcium to 100 microM, but was not intrinsically voltage dependent. CONCLUSIONS The marked dilation of cerebral vessels seen during surgical anesthesia with halothane cannot be attributed to direct effects of the drug on large-conductance calcium-dependent potassium channels. The protective effect of calcium suggests that halothane exerts its effects at channel sites located within the cell membrane.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009131	Muscle, Smooth, Vascular	The nonstriated involuntary muscle tissue of blood vessels.	Vascular Smooth Muscle,Muscle, Vascular Smooth,Muscles, Vascular Smooth,Smooth Muscle, Vascular,Smooth Muscles, Vascular,Vascular Smooth Muscles
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
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
D002536	Cerebral Arteries	The arterial blood vessels supplying the CEREBRUM.	Arteries, Cerebral,Artery, Cerebral,Cerebral Artery
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D006221	Halothane	A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)	1,1,1-Trifluoro-2-Chloro-2-Bromoethane,Fluothane,Ftorotan,Narcotan
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
D014664	Vasodilation	The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.	Vasodilatation,Vasorelaxation,Vascular Endothelium-Dependent Relaxation,Endothelium-Dependent Relaxation, Vascular,Relaxation, Vascular Endothelium-Dependent,Vascular Endothelium Dependent Relaxation
D015221	Potassium Channels	Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.	Ion Channels, Potassium,Ion Channel, Potassium,Potassium Channel,Potassium Ion Channels,Channel, Potassium,Channel, Potassium Ion,Channels, Potassium,Channels, Potassium Ion,Potassium Ion Channel