ABSTRACT
Prostaglandin E(2) (PGE(2)) exerts diverse biological effects through four G-protein-coupled cell surface receptor subtypes, EP1-4. This study's objective was to characterize EP1-4 receptor mRNA expression within pregnant guinea pig myometrium during early implantation stage (gestation day [GD] 6) and late stage gestation (GD 50) and evaluate in vitro contractile activity of receptor subtype selective agonists. Using RT-PCR, qualitative gene expression patterns of EP2, EP3, and EP4 mRNA were detected in the myometrium and remained unchanged between the gestational ages. EP1 mRNA remained undetected in pregnant tissue. In vitro contractile activity was evaluated in GD 6 and GD 50 myometrium using vehicle and EP agonists PGE(2), 17-phenyl trinor PGE(2), sulprostone, misoprostol, and CP-533,536. All spasmogens in pregnant myometrium were EP1/EP3 selective agonists, though likely acting via EP3 receptors in this test model. CP-533,536--a highly selective EP2 receptor agonist--and the vehicle failed to induce myometrial contraction at both gestational ages.
Subject(s)
Myometrium/metabolism , Receptors, Prostaglandin E/metabolism , Uterine Contraction , Uterus/metabolism , Animals , Dinoprostone/pharmacology , Female , Gestational Age , Guinea Pigs , Myometrium/drug effects , Oxytocics/pharmacology , Pregnancy , Pyridines/pharmacology , Receptors, Prostaglandin E/agonists , Receptors, Prostaglandin E, EP2 Subtype , Uterine Contraction/drug effects , Uterus/drug effectsABSTRACT
CP-96,345, a non-peptide, selective tachykinin NK1 receptor blocker and its inactive enantiomer, CP-96,344, inhibit ligand binding of phenylalkylamine but not dihydropyridine Ca2+ channel antagonists. Whether these Ca2+ channel antagonist properties of CP-96,345 and CP-96,344 can be expressed as cardiovascular effects in vitro and in vivo is unknown. The cardiovascular effects of CP-96,345 and CP-96,344 in isolated vascular smooth muscle and in anesthetized dogs were compared to those of verapamil and nifedipine, phenylalkylamine and dihydropyridine Ca2+ channel antagonists, respectively. CP-96,345, CP-96,344, verapamil and nifedipine inhibited Ca(2+)-induced contractions in rat isolated portal vein with pD2' values of 5.9, 5.8, 6.8 and 8.1, respectively. In closed chest, anesthetized, spinal-pithed dogs, CP-96,345 caused dose-related hypotension and depressed heart rate. In open chest, anesthetized beagles at equihypotensive doses, CP-96,345, 1 mg/kg, CP-96,344, 1 mg/kg and verapamil, 0.5 mg/kg caused significant negative chronotropic, dromotropic and inotropic effects that were not observed with nifedipine, 0.01 mg/kg or nitroglycerin, 0.02 mg/kg. We conclude that the cardiovascular effects of CP-96,345 and its isomer are due to 'verapamil-like' Ca2+ channel antagonism and are not related to blockade of NK1 receptors.
Subject(s)
Biphenyl Compounds/pharmacology , Calcium Channel Blockers/pharmacology , Hemodynamics/drug effects , Muscle, Smooth, Vascular/drug effects , Neurokinin-1 Receptor Antagonists , Vasoconstriction/drug effects , Animals , Blood Pressure/drug effects , Calcium/pharmacology , Cells, Cultured , Dogs , Dose-Response Relationship, Drug , Female , Heart Rate/drug effects , In Vitro Techniques , Male , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/cytology , Portal Vein/drug effects , Rats , Rats, Sprague-DawleyABSTRACT
The effects of substance P, neurokinin A, neurokinin B, [Sar9, Met(O2)11]-substance P, [Nle10]-neurokinin A (4-10) and senktide (succinyl-[Asp6, MePhe8]-substance P (6-11)) on blood pressure and heart rate were studied in anesthetized dogs. Dose-dependent decreases in blood pressure and increases in heart rate were caused by each peptide except senktide. The latter elicited weak hypotensive or hypertensive responses at high doses. The order or potency was as follows: [Sar9, Met(O2)11]-substance P greater than or equal to substance P greater than neurokinin A greater than neurokinin B greater than [Nle10]-neurokinin A (4-10) much greater than senktide. CP-96,345, [(2S,3S)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)-methyl]-1- azabicyclo[2.2.2]octan-3-amine] a selective NK-1 tachykinin receptor blocker, inhibited substance P-induced hypotension in a dose-related manner. Responses to each of the other peptides were inhibited by CP-96,345, 1.0 mg/kg (excluding senktide against which CP-96,345 was not tested). CP-96,344 (1.0 mg/kg i.v.) the 2R-3R enantiomer of CP-96,345 which does not block NK-1 receptors, had no effect on substance P-induced hypotension. We conclude that tachykinin-induced hypotension in dogs is mediated by NK-1 tachykinin receptors.
Subject(s)
Biphenyl Compounds/pharmacology , Blood Pressure/drug effects , Receptors, Neurotransmitter/antagonists & inhibitors , Tachykinins/antagonists & inhibitors , Animals , Decerebrate State , Dogs , Dose-Response Relationship, Drug , Female , Heart Rate/drug effects , In Vitro Techniques , Isoproterenol/pharmacology , Male , Neurokinin A/pharmacology , Peptide Fragments/pharmacology , Receptors, Tachykinin , Stereoisomerism , Substance P/analogs & derivatives , Substance P/pharmacologyABSTRACT
CP-96,345 [(2S, 3S)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)- methyl]-1-azabicyclo[2.2.2]octan-3-amine] is a potent nonpeptide antagonist of the substance P (NK1) receptor. CP-96,345 inhibited 3H-labeled substance P binding and was a classical competitive antagonist in the NK1 monoreceptor dog carotid artery preparation. CP-96,345 inhibited substance P-induced salivation in the rat, a classical in vivo bioassay, but did not inhibit NK2, NK3, or numerous other receptors; it is thus a selective NK1 antagonist. This compound may prove to be a powerful tool for investigation of the physiological properties of substance P and exploration of its role in diseases.
Subject(s)
Biphenyl Compounds/pharmacology , Receptors, Neurotransmitter/antagonists & inhibitors , Animals , Binding, Competitive , Biphenyl Compounds/chemistry , Carotid Arteries/drug effects , Cattle , Dogs , Molecular Structure , Muscle Contraction/drug effects , Muscle Relaxation/drug effects , Rabbits , Rats , Receptors, Neurokinin-1 , Salivation/drug effects , Stereoisomerism , Substance P/metabolism , Substance P/pharmacologyABSTRACT
Neurokinin A, neurokinin B and substance P caused concentration-related contractions of rabbit isolated aorta with pD2 values of 8.1, 6.9, and 6.0, respectively. [D-Pro2, D-Trp7, 9]-substance P, a competitive tachykinin antagonist, had pA2 values of 5.3 against neurokinin A, 5.1 against neurokinin B and 5.2 against substance P indicating that tachykinin receptors mediated responses to the agonists. [pGlu5,MePhe8,-MeGly9]-substance P 5 - 11 (DiMe-C7), senktide and septide did not contract the aorta. It is concluded that of the known tachykinin receptors smooth muscle of the rabbit isolated aorta contains only the NK-2 type.
Subject(s)
Muscle, Smooth, Vascular/ultrastructure , Receptors, Neurotransmitter/metabolism , Animals , Aorta, Thoracic/drug effects , Aorta, Thoracic/physiology , Aorta, Thoracic/ultrastructure , Female , Kinetics , Male , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/physiology , Neurokinin A/pharmacology , Neurokinin B/pharmacology , Rabbits , Receptors, Neurotransmitter/physiology , Receptors, Tachykinin , Substance P/analogs & derivatives , Substance P/pharmacologyABSTRACT
A vehicle containing ethanol and Emulphor EL620 lowers blood pressure and increases heart rate in morphine-chloralose anesthetized dogs. These effects are associated with histamine release caused by Emulphor EL620.
