Properties and functions of a neuromedin-B-preferring bombesin receptor in brain microvascular endothelial cells.
Endothelial cells were isolated from rat brain microvessels and grown in vitro. They expressed a high density of [125I-Tyr4]bombesin receptor (Bmax = 0.9 pmol/mg protein) with an apparent Kd value of 10 nM. The pharmacological profile of inhibition of the specific [125I-Tyr4]bombesin binding [bombesin = neuromedin B > gastrin releasing peptide (GRP)] was consistent with the presence of a neuromedin-B-preferring receptor. Addition of bombesin, neuromedin B and GRP increased the activity of phospholipase C as measured by the production of total inositol phosphates and from intracellular Ca2+ measurements. They increase 86Rb+ uptake by the Na+, K+, 2Cl- cotransporter and by a charybdotoxin-sensitive, Ca(2+)-activated K+ channel and 22Na+ uptake by the Na+/H+ exchanger. The pharmacological profiles of activation of phospholipase C, Na+, K+, 2Cl- cotransport and Na+/H+ exchange by bombesin-like peptide were consistent with an involvement of the neuromedin-B-preferring receptor characterized in binding experiments. It is suggested that one of the actions of neuromedin B in brain vessels could be to control K+ secretion by the blood/brain barrier.
Vigne
P
P
Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Valbonne, France.
Feolde
E
E
Van Renterghem
C
C
Breittmayer
J P
JP
Frelin
C
C
D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D008833:Microcirculation / Q000378:metabolism; D015287:Neurokinin B / Q000031:analogs & derivatives* / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D018004:Receptors, Bombesin / Q000032:analysis / Q000502:physiology*; D012413:Rubidium / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D018004:Receptors, Bombesin; D015287:Neurokinin B; C038393:neuromedin B; D010738:Type C Phospholipases; D012413:Rubidium; D001839:Bombesin; D011188:Potassium; D002118:Calcium