In intact cultured rabbit corneal cells we have identified [3H]dihydroalprenolol ([3H]DHA) and [3H]quinuclidinyl benzilate ([3H]QNB) binding activities which meet criteria for β-adrenergic and muscarinic cholinergic receptors. For saturable, propranolol-sensitive [3H]DHA binding, B(max)=0.374 ± 0.063 fmol/μg protein; K(DHA)=12.5 ± 2.4 nM from Scatchard analysis. For saturable, atropine-sensitive [3H]QNB binding, B(max)=0.403 ± 0.053 fmol/μg protein; K(QNB)=15.4 ± 0.7 nM. The order of potency of unlabeled adrenergic agonists in competition for [3H]DHA sites was isoproterenol>epinephrine>norepinephrine. For unlabeled cholinergic agonists competing for [3H]QNB sites, the order was oxotremorine>acetylcholine≥carbamylcholine. Acetylcholine did not inhibit [3H]DHA binding, nor did isoproterenol or choline inhibit [3H]QNB binding. Effectiveness of drugs in stimulating cAMP or cGMP accumulation closely paralleled efficacy in competition for [3H]DHA or [3H]QNB sites. Results confirm the presence in intact cultured corneal membrane suspensions), identify in intact cells muscarinic cholinergic receptors (not previously detected in broken cell preparations), and supply evidence for receptor-mediated regulation of cyclic nucleotide levels in these cells, further supporting our hypothesis of bidirectional influence by cAMP-mediated β-adrenergic and cGMP-mediated cholinergic 'first messengers' on proliferation during healing of corneal epithelial defects.
|Original language||English (US)|
|Number of pages||12|
|Journal||Metabolic, Pediatric and Systemic Ophthalmology|
|State||Published - Jan 1 1982|
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Endocrinology, Diabetes and Metabolism