Biomaterial Database

Effect of voltage and cyclic AMP on frequency of slow-wave-type action potentials in canine colon smooth muscle. 1991

J D Huizinga, and L Farraway, and A Den Hertog

Intestinal Disease Research Unit, McMaster University, Hamilton, Ontario, Canada.

1. A non-L-type calcium conductance is involved in the generation of the initial part of the slow-wave-type action potential in colonic smooth muscle. The present study addresses the question whether this conductance is voltage or metabolically activated. 2. Current-induced hyperpolarization increased frequency and amplitude of slow waves measured in Krebs solution. 3. The upstroke potential was 'isolated' from the slow wave by superfusion with 'glucamine-nitrendipine' Krebs solution (NaCl was replaced by glucamine, nitrendipine was added). 4. Hyperpolarization up to -100 mV did not affect the upstroke potential frequency and increased its amplitude. Only hyperpolarization further than -100 mV decreased the frequency less than or equal to 20%, and reduced the amplitude less than or equal to 20%. 5. Depolarization did not affect the upstroke potential frequency. 6. Forskolin, but not 1,9-dideoxyforskolin dramatically decreased the upstroke potential frequency, without affecting other parameters including the resting membrane potential. 7. The effect of forskolin was mimicked by dibutyryl cyclic AMP, 8-bromo-cyclic AMP and 3-isobutyl-1-methylxanthine (IBMX), but not extracellular cyclic AMP. 8. The upstroke potential could not be evoked by depolarizing pulses after inhibition of activity by forskolin. 9. The effect of forskolin could be reversed by the calcium ionophore A23187. 10. In summary, voltage changes up to -40 mV and down to -100 mV do not, but changes in intracellular cyclic AMP do affect the frequency of the upstroke potential. 11. It is likely that intracellular metabolic activity, which may include cyclic AMP but not a voltage change, activates the conductance responsible for the generation of the upstroke potential.

UI	MeSH Term	Description	Entries
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
D010726	Phosphodiesterase Inhibitors	Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.	Phosphodiesterase Antagonists,Phosphodiesterase Inhibitor,Phosphoric Diester Hydrolase Inhibitors,Antiphosphodiesterases,Inhibitor, Phosphodiesterase
D003106	Colon	The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.	Appendix Epiploica,Taenia Coli,Omental Appendices,Omental Appendix,Appendices, Omental,Appendix, Omental
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D005576	Colforsin	Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland.	Coleonol,Forskolin,N,N-Dimethyl-beta-alanine-5-(acetyloxy)-3-ethenyldodecahydro-10,10b-dihydroxy-3,4a,7,7,10a-pentamethyl-1-oxo-1H-naphtho(2,1-b)pyran-6-yl Ester HCl,NKH 477,NKH-477,NKH477
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
D000242	Cyclic AMP	An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.	Adenosine Cyclic 3',5'-Monophosphate,Adenosine Cyclic 3,5 Monophosphate,Adenosine Cyclic Monophosphate,Adenosine Cyclic-3',5'-Monophosphate,Cyclic AMP, (R)-Isomer,Cyclic AMP, Disodium Salt,Cyclic AMP, Monoammonium Salt,Cyclic AMP, Monopotassium Salt,Cyclic AMP, Monosodium Salt,Cyclic AMP, Sodium Salt,3',5'-Monophosphate, Adenosine Cyclic,AMP, Cyclic,Adenosine Cyclic 3',5' Monophosphate,Cyclic 3',5'-Monophosphate, Adenosine,Cyclic Monophosphate, Adenosine,Cyclic-3',5'-Monophosphate, Adenosine,Monophosphate, Adenosine Cyclic
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