[3H]mepyramine binding sites, histamine H1-receptors, in bovine retinal blood vessels.
The presence of histamine H1-receptors in the bovine retinal blood vessels was studied with a [3H]mepyramine binding assay. The membranes of purified vessels obtained from bovine retinas showed specific [3H]mepyramine binding sites with a dissociation constant (KD) of 2.78 +/- 0.32 nM. This was similar to values obtained from the retinal neuronal fractions. The binding capacity (Bmax) was 53.8 +/- 1.7 fmol/mg protein, which was about a half that of the retinal neuronal fractions (108.9 +/- 3.1 fmol/mg protein). Some H1-antagonists proved to be potent competitors for [3H]mepyramine binding sites in bovine retinal blood vessels. These results indicate that histamine H1-receptors exist in the retinal blood vessels which may be involved in the physiological and the pathological responses of blood circulation in retinas.
Department of Ophthalmology, Osaka University Hospital, Japan.
S
S
Sawai
H
H
Fukui
M
M
Fukuda
N P
NP
Wang
H
H
Wada
R
R
Manabe
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D002417:Cattle; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D007700:Kinetics; D011738:Pyrilamine / Q000378:metabolism*; D011869:Radioligand Assay; D011969:Receptors, Histamine H1 / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D012171:Retinal Vessels / Q000378:metabolism*
D006634:Histamine H1 Antagonists; D011969:Receptors, Histamine H1; D011738:Pyrilamine