Changing sensitivity to H1 and H2 receptor antagonists in the growing vasculature.
1. Resting albumin efflux is greater from immature vessels than from mature and this is associated with a greater blood flow in immature vessels. 2. Both resting blood flow and albumin efflux in immature vessels are reduced by an H2 antagonist. 3. Histamine produces a greater albumin efflux from mature vessels than from immature and the associated increase in blood flow in response to histamine was also greater in mature vessels. 4. Blood flow and permeability increase produced by histamine are separately mediated via H2 and H1 receptors respectively in mature vessels. 5. In immature vessels, H2 receptors appear to mediate both responses.
Smaje
L H
LH
Department of Physiology, Charing Cross and Westminster Medical School, London, UK.
Noor
N M
NM
Clough
G F
GF
D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001808:Blood Vessels / Q000187:drug effects / Q000254:growth & development*; D002199:Capillary Permeability / Q000187:drug effects; D002927:Cimetidine / Q000494:pharmacology; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D008297:Male; D009389:Neovascularization, Pathologic; D019736:Prostheses and Implants; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000187:drug effects
D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D002927:Cimetidine; D006632:Histamine; D011738:Pyrilamine