title: Role of the efferent arteriole in glomerular hemodynamics of superficial nephrons.
abstract: Hemodynamic pressure in glomerular capillaries (GCP) and in first order peritubular capillaries (EAP) in superficial nephrons of mutant Wistar rats with surface glomeruli was measured by micropuncture with a servo-nulling device in the following conditions: 1) control;2) norepinephrine infusion (NE); 3) epinephrine infusion (E): 4) dopamine infusion (D); 5) hemorrhagic hypotension (HH); 6) HH + NE; 7) HH + E; 8) HH + D; 9) acute hypertension secondary to bilateral cervical vagotomy and occlusion of both common carotid arteries. BP was also recorded. Both GCP/BP and EAP/GCP ratios averaged 0.40 in control conditions, but only the EAP/GCP ratio remained constant in all conditions under study, indicating that approximately 60% of the hydrostatic pressure in glomerular capillaries is constantly dissipated by the efferent arteriole. When all values of EAP were plotted against the respective values of GCP, a liner relationship was detected (r=0.843). These results indicate that changes of pressure in the first order peritubular capillaries of superficial nephrons are merely secondary to changes in glomerular capillary pressure.
mesh_terms: D000208:Acute Disease; D000818:Animals; D002196:Capillaries; D004298:Dopamine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006439:Hemodynamics; D006973:Hypertension; D007678:Kidney Glomerulus / Q000098:blood supply*; D008833:Microcirculation; D009399:Nephrons / Q000098:blood supply; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D012039:Regional Blood Flow; D014628:Vagotomy
chemical_list: D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine