Effects of intracisternal endothelin-1 injection on blood flow to the lower brain stem.
The central effects of endothelin-1 (Et-1, 10-30 pmol in 2.5 microliters injected intracisternally) have been investigated in the conscious rat. With 10 and 20 pmol Et-1, no significant change in blood pressure was observed. With 30 pmol Et-1, mean arterial blood pressure rose by 40 +/- 10 mm Hg with an accompanying modest, short-lived bradycardia at 2 min post-injection. Cerebral blood flow [( 14C]iodoantipyrine autoradiography), measured simultaneously with the hypertensive response, was markedly reduced throughout the caudal medulla and cerebellum (by up to 85%), while significant hyperaemia was evident in a number of forebrain structures (e.g. an increase of 78% in sensorimotor cortex). These observations have relevance to two distinct scientific areas. Concerning the significant effect of Et-1 in central cardiovascular control, these results caution against drawing conclusions from ventricular application with knowledge only of cardiovascular parameters. These results also illustrate the profound effects of Et-1 which is uniquely capable of overriding cerebral autoregulatory mechanisms.
Macrae
I
I
University Department of Medicine and Therapeutics, Western Infirmary, Gardiner Institute, Glasgow, U.K.
Robinson
M
M
McAuley
M
M
Reid
J
J
McCulloch
J
J
D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives; D001345:Autoradiography; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D002946:Cisterna Magna; D016232:Endothelins / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D007267:Injections; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology; D016548:Prosencephalon / Q000098:blood supply / Q000502:physiology; D051381:Rats; D011921:Rats, Inbred WKY
D016232:Endothelins; D000983:Antipyrine; C008135:iodoantipyrine