title: Altered endothelin-1 induced contraction and second messenger generation in bovine retinal microvascular pericytes cultured in high glucose medium.
abstract: The effect of simulated hyperglycaemia on bovine retinal pericytes was studied following culture of these cells for 10 days under normal (5 mmol/l) and elevated (25 mmol/l) glucose conditions in the absence of endothelial cells. Pericytes cultured under high ambient glucose exhibited both a delayed and reduced contractile response following stimulation with endothelin-1. Stimulation with 10(-7) mol/l endothelin-1 for 30 s caused significant contraction in cells grown in both 5 mmol/l and 25 mmol/l glucose. The former also contracted significantly with 10(-8) mol/l endothelin-1. Further, at all concentrations tested, statistical comparison of the time course of contraction showed a significant difference (p < 0.02) in the reduction of planimetric surface area between the two cell groups. Since neither binding of endothelin-1 nor the number of receptors for this peptide were significantly different (p > 0.1) between bovine retinal pericytes grown for 10 days under normo- or hyperglycaemic conditions, it became apparent that the altered contractility in bovine retinal pericytes following culture in high glucose must be due to post-binding intracellular disturbance(s). Indeed, both basal and 15 s post-stimulation with 10(-8) mol/l endothelin-1, levels of inositol trisphosphate were significantly reduced (p < 0.05 and p < 0.02, respectively) in pericytes cultured for 10 days in 25 mmol/l glucose. These results show that endothelial-independent alterations in contractility of pericytes occur when they are grown in conditions which simulate hyperglycaemia. The results also suggest that the observed attenuation in response to endothelin-1 stimulation evident in pericytes grown under simulated hyperglycaemic conditions is not due to alterations in peptide binding.
authors.affiliation: Department of Ophthalmology, Queen's University of Belfast, UK.
authors.forename: U
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: A
authors.initials: A
authors.lastname: McGinty
authors.forename: J
authors.initials: J
authors.lastname: McKillop
authors.forename: P
authors.initials: P
authors.lastname: Anderson
authors.forename: D B
authors.initials: DB
authors.lastname: Archer
authors.forename: E R
authors.initials: ER
authors.lastname: Trimble
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D016232:Endothelins / Q000378:metabolism / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007457:Iodine Radioisotopes; D008833:Microcirculation / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D012171:Retinal Vessels / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D015290:Second Messenger Systems / Q000187:drug effects / Q000502:physiology*
chemical_list: D003470:Culture Media; D016232:Endothelins; D007457:Iodine Radioisotopes; D015544:Inositol 1,4,5-Trisphosphate; D005947:Glucose