Related Experiment Video
Updated: Jun 27, 2026
10:02
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Pharmacological evaluation of ocular beta-adrenoceptors in rabbit by tissue segment binding method
Takahiro Horinouchi1, Shigeru Morishima, Yoshio Tanaka
1Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui, Eiheiji, Fukui 910-1193, Japan.
Life Sciences
|December 18, 2008
Summary
This study reveals that the binding affinity of beta-adrenoceptor antagonists is higher for (-)-enantiomers than (+)-enantiomers, with varying stereoselectivity across different beta-adrenoceptor subtypes in rabbit tissues.
Area of Science:
- Pharmacology
- Ocular Pharmacology
- Cardiovascular Pharmacology
Background:
- Beta-adrenoceptors play crucial roles in various physiological processes.
- Understanding the binding characteristics of beta-adrenoceptor antagonists is essential for drug development.
- Ocular tissues possess distinct beta-adrenoceptor populations influencing intraocular pressure and other functions.
Purpose of the Study:
- To characterize plasma membrane beta-adrenoceptors in ocular and nonocular rabbit tissues.
- To determine the binding affinities of various beta-adrenoceptor antagonists.
- To investigate the stereoselectivity of beta-adrenoceptor antagonists.
Main Methods:
- Utilized the tissue segment binding method with the hydrophilic radioligand ([(3)H])-CGP12177.
- Employed competition experiments with selective beta(1)- and beta(2)-adrenoceptor antagonists.
- Analyzed binding data to determine receptor populations and antagonist affinities.
Main Results:
- Identified single populations of beta(2)-adrenoceptors in ocular tissues and beta(1)-adrenoceptors in atria.
- Detected mixed beta(1)- and beta(2)-adrenoceptor populations in rabbit lung.
- Demonstrated higher binding affinity for (-)-enantiomers of beta-adrenoceptor antagonists compared to their (+)-enantiomers, with varying stereoselectivity.
Conclusions:
- The study elucidates the differential binding characteristics of beta-adrenoceptor antagonists in various rabbit tissues.
- Findings highlight the importance of stereochemistry in the interaction of antagonists with beta-adrenoceptor subtypes.
- This research contributes to a better understanding of beta-adrenoceptor pharmacology and antagonist selectivity.
Related Concept Videos
01:26Adrenergic Receptors: β Subtype
β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
01:27Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers
β-receptor blockers significantly impact the cardiovascular system by counteracting catecholamine-induced sympathetic responses. These medications decrease heart rate, contractility, and cardiac output, potentially leading to cardiac depression, life-threatening bradycardia, and death. Therapeutically, β-blockers function as mild antihypertensives and are utilized in treating angina pectoris and cardiac arrhythmias. However, nonselective β-blockers inhibit β2-receptors in bronchial smooth...
01:25Adrenergic Antagonists: Chemistry and Classification of β-Receptor Blockers
β-adrenergic antagonists, or β-blockers, modulate the sympathetic nervous system by targeting β-adrenoceptors and inhibiting catecholamine-mediated sympathetic responses. β-blockers differ in their adrenoceptor subtype affinity, lipophilicity, and α-blocking capabilities. The history of β-blocker development began with the prototype, dichloroisoprenaline, which exhibited partial agonist activity. As a result, propranolol was developed as a pure antagonist but nonselective agent, paving the way...
01:17Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers
Adrenergic antagonists, or sympatholytics, inhibit adrenoceptor activation driven by catecholamines or agonists. Based on their adrenoceptor specificity, adrenergic blockers can be categorized into two primary groups: α-adrenergic blockers (α-blockers) and β-adrenergic blockers (β-blockers). α-blockers interact with α1 and α2 subtypes of α-adrenoceptors.
Nonselective α-blockers: Nonselective α-blockers contain haloalkylamine or imidazoline moieties. Phenoxybenzamine, with a haloalkylamine...
Nonselective α-blockers: Nonselective α-blockers contain haloalkylamine or imidazoline moieties. Phenoxybenzamine, with a haloalkylamine...
01:27Adrenergic Receptors (Adrenoceptors): Classification
Adrenergic receptors, or adrenoceptors, respond to the autonomic neurotransmitter noradrenaline and other endogenous catecholamine agonists. They are classified into two main families, α and β, based on their pharmacological response and are further subdivided depending on their location, elicited response, and affinity to specific agonists or antagonists.
α-Adrenoceptors
α-Adrenoceptors are classified into two main subtypes: α1 and α2. The α1 adrenoceptors, which are found on postsynaptic...
α-Adrenoceptors
α-Adrenoceptors are classified into two main subtypes: α1 and α2. The α1 adrenoceptors, which are found on postsynaptic...
01:31Adrenergic Receptors: ɑ Subtype
Adrenoceptors are classified into α and ꞵ classes based on their potencies to catecholamine agonists. α-adrenoceptors show the following order of catecholamine potency:
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase C—inositol-1,4,5-trisphosphate...
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase C—inositol-1,4,5-trisphosphate...