Spinal cord blood flow decreases following chemical stimulation of the rostral ventrolateral medullary pressor area in anesthetized rats.
In urethane-anesthetized, paralyzed and artificially ventilated rats, the neurons in the rostral ventrolateral medullary pressore area (VLPA) were chemically stimulated by microinjections of L-glutamate (1.7-5.0 nmol in 100 nl of 0.9% sodium chloride solution) and the spinal cord blood flow (SCBF) was determined using a combination of labeled microspheres (57Co, 113Sn and 46Sc). In order to measure SCBF at normotension, moderate hypotension within the lower limit of spinal cord autoregulation was induced by controlled hemorrhage (n = 12). Unilateral chemical stimulation of the VLPA in these rats increased arterial blood pressure (ABP) but it remained within normotensive range. The SCBFs of cervical, thoracic and lumbar cord decreased significantly from 27 +/- 3 (mean +/- S.E.M.) to 20 +/- 2 (P less than 0.01), from 22 +/- 1 to 17 +/- 2 (P less than 0.05), and from 41 +/- 5 to 26 +/- 3 (P less than 0.05) ml.min-1.(100 g)-1, respectively. The spinal cord vascular resistances (SCVRs) of cervical, thoracic and lumbar cord increased significantly from 3.7 +/- 0.4 to 5.0 +/- 0.6 (P less than 0.05), from 4.2 +/- 0.2 to 5.9 +/- 0.7 (P less than 0.05), and from 2.5 +/- 0.2 to 3.8 +/- 0.4 (P less than 0.05) mmHg per [ml.min-1.(100 g)-1], respectively. During the chemical stimulation of the VLPA, SCBF increased in response to the changes in arterial PaCO2 indicating that the reactivity of spinal cord vasculature was intact (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)
Maeda
M
M
Section of Neurological Surgery, UMDNJ-New Jersey Medical School, Newark.
Krieger
A J
AJ
Nakai
M
M
Sapru
H N
HN
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D007276:Injections, Intraventricular; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects*; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects*; D013116:Spinal Cord / Q000098:blood supply*; D014520:Urethane
D005971:Glutamates; D014520:Urethane; D018698:Glutamic Acid