H2-receptors mediate histamine-induced variations in the permeability of the blood-brain barrier of rats.
Earlier investigations suggested that histamine H2-receptors mediate alterations in cerebrovascular permeability in mammals. The objective of this study was to observe the effects of the H2-receptor antagonist ranitidine on histamine-stimulated alterations in the permeability of the blood-brain barrier (BBB) of rats. Normotensive Wistar-Kyoto (WKY) (control) and spontaneously hypertensive (SHR) rats were premedicated with ranitidine (1 mg/kg), followed by histamine (1.25, 2.5 or 5.0 micrograms/kg) or saline. Animals were anesthetized and permeability of the BBB was evaluated with 99mTc-labeled sodium pertechnetate (TcO4-) or with 131I-labeled human serum albumin (RISA). In both control and hypertensive rats, ranitidine blocked histamine-induced changes in cerebrovascular permeability, but did not inhibit histamine-stimulated systemic hypotension. The alterations in the permeability of the BBB did not correlate with variations in blood pressure produced by histamine.
Boertje
S B
SB
Department of Biology, Southern University at New Orleans, Louisiana 70126.
Ward
S
S
Robinson
A
A
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001812:Blood-Brain Barrier / Q000187:drug effects*; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D008297:Male; D010539:Permeability / Q000187:drug effects; D011899:Ranitidine / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011970:Receptors, Histamine H2 / Q000187:drug effects*; D012711:Serum Albumin, Radio-Iodinated; D013670:Sodium Pertechnetate Tc 99m
D011970:Receptors, Histamine H2; D012711:Serum Albumin, Radio-Iodinated; D006632:Histamine; D011899:Ranitidine; D013670:Sodium Pertechnetate Tc 99m