Biomaterial Database

Effects of 8-bromo-cyclic GMP on membrane potential of single swine tracheal smooth muscle cells. 1998

J Choi, and J M Farley

Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, USA.

Cyclic GMP relaxes swine tracheal smooth muscle. Relaxation occurs because of decreases in intracellular calcium concentration ([Ca++]i) that are thought to occur through hyperpolarization which inhibits calcium influx. Activation of K+ channels has been suggested as the underlying mechanism for the hyperpolarization. In the present study, the effects of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP, a membrane-permeable analog of cyclic GMP) on acetylcholine (ACh)-induced increases in [Ca++]i were examined by laser scanning confocal microscopy in fluo 3-loaded single cells. Membrane potential and currents were measured by the perforated-configuration of patch-clamp method, 8-Bromo-cGMP (1 microM-0.1 mM) inhibited 0.1 microM ACh-induced oscillations in [Ca++]i in a concentration-dependent manner. Spontaneous changes in membrane potential were observed by the patch-clamp method. Acetylcholine (0.03 microM) did not affect the time-averaged mean potential. The spontaneous changes in membrane potential were reduced and the cells were depolarized by 0.1 microM ACh and to a greater degree by 1 microM ACh. This result is consistent with previous observations of ACh-induced depolarization in intact tissue. The application of 0.1 mM 8-Br-cGMP had no significant effects on spontaneous changes in membrane potential and did not induce changes in membrane potential in cells treated with 0.1 microM ACh. In voltage-clamped cells, ACh (0.1 microM) induced oscillations in calcium-activated K+ currents. 8-Bromo-cGMP (0.1 mM) inhibited these ACh-induced oscillations in currents, but had no significant effects on spontaneous changes in membrane current in unstimulated cells. These data indicate that 8-Br-cGMP inhibits ACh-induced increases in [Ca++]i by mechanisms other than regulation of membrane potential.

UI	MeSH Term	Description	Entries
D008297	Male		Males
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
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
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
D006152	Cyclic GMP	Guanosine cyclic 3',5'-(hydrogen phosphate). A guanine nucleotide containing one phosphate group which is esterified to the sugar moiety in both the 3'- and 5'-positions. It is a cellular regulatory agent and has been described as a second messenger. Its levels increase in response to a variety of hormones, including acetylcholine, insulin, and oxytocin and it has been found to activate specific protein kinases. (From Merck Index, 11th ed)	Guanosine Cyclic 3',5'-Monophosphate,Guanosine Cyclic 3,5 Monophosphate,Guanosine Cyclic Monophosphate,Guanosine Cyclic-3',5'-Monophosphate,3',5'-Monophosphate, Guanosine Cyclic,Cyclic 3',5'-Monophosphate, Guanosine,Cyclic Monophosphate, Guanosine,Cyclic-3',5'-Monophosphate, Guanosine,GMP, Cyclic,Guanosine Cyclic 3',5' Monophosphate,Monophosphate, Guanosine Cyclic
D000109	Acetylcholine	A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.	2-(Acetyloxy)-N,N,N-trimethylethanaminium,Acetilcolina Cusi,Acetylcholine Bromide,Acetylcholine Chloride,Acetylcholine Fluoride,Acetylcholine Hydroxide,Acetylcholine Iodide,Acetylcholine L-Tartrate,Acetylcholine Perchlorate,Acetylcholine Picrate,Acetylcholine Picrate (1:1),Acetylcholine Sulfate (1:1),Bromoacetylcholine,Chloroacetylcholine,Miochol,Acetylcholine L Tartrate,Bromide, Acetylcholine,Cusi, Acetilcolina,Fluoride, Acetylcholine,Hydroxide, Acetylcholine,Iodide, Acetylcholine,L-Tartrate, Acetylcholine,Perchlorate, Acetylcholine
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
D013552	Swine	Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).	Phacochoerus,Pigs,Suidae,Warthogs,Wart Hogs,Hog, Wart,Hogs, Wart,Wart Hog
D014132	Trachea	The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.	Tracheas