Biomaterial Database

Alpha 1-adrenoceptors in guinea-pig heart ventricles. [3H]prazosin and [125I]IBE 2254 are bound specifically to a receptor population with high affinity and low density. 1987

C U Rugevics, and H J Schümann

Pharmakologisches Institut, Universitäts-Klinikum Essen, F.R.G.

In membrane preparations of guinea-pig heart ventricles [3H]prazosin ([3H]PRAZ) and [125I]-2-[beta-(4-hydroxy-3-iodophenyl)ethylaminoethyl]tetralone ([125I]IBE 2254) were used to determine the quantity and the characteristics of the small number of alpha 1-adrenoceptors. The amount of alpha 1-adrenoceptors was compared with the quantity of beta-adrenoceptors which were determined by [3H]dihydroalprenolol ([3H]DHA) binding. Equilibrium binding of all radioligands was found to be of high affinity, high specificity and saturable. A single homogeneous population of binding sites was labelled with the radioligands. The results of kinetic experiments with [3H]PRAZ and [125I]IBE 2254 confirmed the equilibrium binding results. In competition experiments, the rank order of potency for antagonists and agonists to compete with both radioligands was consistent with the well-established rank order at the alpha 1-adrenoceptor. In competition experiments, (-)-noradrenaline was more potent in inhibiting specific binding of [3H]PRAZ and [125I]IBE 2254 than (+)-noradrenaline by a factor of more than 50. The number of beta-adrenoceptors exceeded those of alpha 1-adrenoceptors by a factor of 4.4. According to our results in ventricles of the guinea-pig heart there exists a small population of alpha 1-adrenoceptors. Therefore, the determination of their number even by an adapted method and by means of radioligands with high specific activity and high selectivity as [3H]PRAZ and [125I]IBE 2254 is difficult.

UI	MeSH Term	Description	Entries
D007457	Iodine Radioisotopes	Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.	Radioisotopes, Iodine
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008297	Male		Males
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010627	Phenethylamines	A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed)	Phenylethylamines
D011224	Prazosin	A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION.	Furazosin,Minipress,Pratsiol,Prazosin HCL,Prazosin Hydrochloride,HCL, Prazosin,Hydrochloride, Prazosin
D011869	Radioligand Assay	Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).	Protein-Binding Radioassay,Radioreceptor Assay,Assay, Radioligand,Assay, Radioreceptor,Assays, Radioligand,Assays, Radioreceptor,Protein Binding Radioassay,Protein-Binding Radioassays,Radioassay, Protein-Binding,Radioassays, Protein-Binding,Radioligand Assays,Radioreceptor Assays
D011942	Receptors, Adrenergic, alpha	One of the two major pharmacological subdivisions of adrenergic receptors that were originally defined by the relative potencies of various adrenergic compounds. The alpha receptors were initially described as excitatory receptors that post-junctionally stimulate SMOOTH MUSCLE contraction. However, further analysis has revealed a more complex picture involving several alpha receptor subtypes and their involvement in feedback regulation.	Adrenergic alpha-Receptor,Adrenergic alpha-Receptors,Receptors, alpha-Adrenergic,alpha-Adrenergic Receptor,alpha-Adrenergic Receptors,Receptor, Adrenergic, alpha,Adrenergic alpha Receptor,Adrenergic alpha Receptors,Receptor, alpha-Adrenergic,Receptors, alpha Adrenergic,alpha Adrenergic Receptor,alpha Adrenergic Receptors,alpha-Receptor, Adrenergic,alpha-Receptors, Adrenergic
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
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