Biomaterial Database

Effects of oxytocin on ionic currents underlying rhythmic activity and contraction in uterine smooth muscle. 1976

J Mironneau

The influence of oxytocin on the electrical and mechanical activity of uterine smooth muscle strips was studied under voltage-clamp conditions. 1. At a concentration of 0.1 mU/ml, oxytocin caused a slight depolarization of the resting potential and also increased the amplitude of the action potential. The maximal frequency of the rhythmic activity, which can be produced by depolarizing current pulse, is increased by about 20%. 2. Oxytocin increased the peak of the inward current without modification of the reversal potential. This effect is enhanced in a sodium-free solution. With oxytocin the steady-state inactivation of the inward current is not modified and the increase in the current intensity can be related to an increase in the maximal conductance. The amplitude of the outward current is not affected. 3. The first component (phasic-like) of the contractile response obtained for brief depolarizations is increased by oxytocin. This effect may be explained by the increase in the intensity of the inward current. The second component (tonic-like) of the contraction associated with long-lasting depolarizations and obtained in manganese-containing solution is not modified. The increased frequency of the rhythmic activity after oxytocin administration may also result in increased contractility by summation.

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
D010121	Oxytocin	A nonapeptide hormone released from the neurohypophysis (PITUITARY GLAND, POSTERIOR). It differs from VASOPRESSIN by two amino acids at residues 3 and 8. Oxytocin acts on SMOOTH MUSCLE CELLS, such as causing UTERINE CONTRACTIONS and MILK EJECTION.	Ocytocin,Pitocin,Syntocinon
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
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
D005260	Female		Females
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
D014590	Uterine Contraction	Contraction of the UTERINE MUSCLE.	Myometrial Contraction,Contraction, Myometrial,Contraction, Uterine,Contractions, Myometrial,Contractions, Uterine,Myometrial Contractions,Uterine Contractions
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus