Cerebrocortical and medullary blood flow changes after general opiate receptor blockade during hemorrhagic shock in cats.
The effect of centrally induced opiate receptor blockade on regional cerebral blood flow (rCBF) was studied in anesthetized, ventilated cats during the course of hemorrhagic shock. The blood flow of the medulla and the parietal cortex was measured with the H2-gas clearance technique. Hemorrhagic shock was produced by lowering the systemic mean arterial pressure to 60 mmHg for 120 min by blood withdrawal. Central opiate receptor blockade was induced by 10 micrograms/kg intracerebroventricularly (i.c.v.) injected naloxone at the 60th min of the bleeding period. Cortical blood flow showed no improvement after i.c.v. naloxone administration. Medullary blood flow, however, increased significantly and approached the pre-bleeding control flow values following central opiate receptor blockade. The results indicate involvement of endogenous opioid mechanisms in the regulation of rCBF during hemorrhage and may provide an explanation for the previously described beneficial effects of naloxone in hemorrhagic shock.
Komjáti
K
K
Experimental Research Department, 2nd Institute of Physiology, Semmelweis University of Medicine, Budapest, Hungary.
Sandor
P
P
Sandor
N
N
Szirmai
L
L
H-Velkei
M
M
Kovach
A G
AG
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide; D002415:Cats; D002540:Cerebral Cortex / Q000098:blood supply* / Q000187:drug effects / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D006470:Hemorrhage / Q000503:physiopathology; D008297:Male; D008526:Medulla Oblongata / Q000098:blood supply* / Q000187:drug effects / Q000503:physiopathology; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010296:Parietal Lobe / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D011957:Receptors, Opioid / Q000187:drug effects* / Q000502:physiology; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D017552:Solitary Nucleus / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology
D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D002245:Carbon Dioxide; D009270:Naloxone