Preferential acetazolamide-induced vasodilation based on vessel size and organ: confirmation of peripheral vasodilation with use of colored microspheres.
When carbonic anhydrase activity decreases, the regional blood flow (rBF) in organs increases as hypercapnia develops. However, the effects of acetazolamide (AZ)-induced vasodilation have not been estimated with respect to vessel size and organs. The aim of this study was to determine the diameter of the capillaries in various organs that respond to inhibition of carbonic anhydrase activity by AZ. White rabbits were anesthetized with urethane and ketamine and infused with AZ. While the systolic blood pressure (SBP), pH, hemoglobin concentration, and base excess did not change, the partial pressure of arterial oxygen (PaO2) increased significantly and the partial pressure of arterial carbon dioxide (PaCO2) decreased significantly with AZ. The rBF was calculated by using 3 different sizes (15, 25, and 50 microm) of colored microspheres (CM). The rBF measured with 15 microm CM in the brain, kidneys, and liver increased in response to AZ, and the rBF in these organs was different with the different sizes of CM. However, the rBF calculated by using the different sizes of CM in the stomach and abdominal muscle did not change after the administration of AZ. The AZ-induced vasodilation occurred in all sizes of vessels in the liver, in the small and medium-sized vessels in kidneys, and in the larger capillaries in the brain.
Taki
K
K
Department of Emergency Medicine, Saga Medical College, Japan.
Oogushi
K
K
Hirahara
K
K
Gai
X
X
Nagashima
F
F
Tozuka
K
K
D000009:Abdominal Muscles / Q000098:blood supply; D000086:Acetazolamide / Q000494:pharmacology*; D000818:Animals; D002196:Capillaries / Q000033:anatomy & histology* / Q000187:drug effects; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D003116:Color; D007668:Kidney / Q000098:blood supply; D008099:Liver / Q000098:blood supply; D008863:Microspheres; D010100:Oxygen / Q000032:analysis; D010313:Partial Pressure; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects; D013270:Stomach / Q000098:blood supply; D014665:Vasodilator Agents / Q000494:pharmacology*
D002257:Carbonic Anhydrase Inhibitors; D014665:Vasodilator Agents; D000086:Acetazolamide; D010100:Oxygen