scholarly journals Opioids and the Prostanoid System in the Control of Cerebral Blood Flow in Hypotensive Piglets

1991 ◽  
Vol 11 (3) ◽  
pp. 380-387 ◽  
Author(s):  
William M. Armstead ◽  
Robert Mirro ◽  
David W. Busija ◽  
Charles W. Leffler

The interaction between opioid and prostanoid mechanisms in the control of cerebral hemodynamics was investigated in the conscious hypotensive piglet. Radiomicrospheres were used to determine regional cerebral blood flow (rCBF) in piglets pretreated with the opioid receptor antagonist, naloxone, or its vehicle, saline, during normotension, hypotension, and after the administration of indomethacin, a cyclooxygenase inhibitor, during hypotension. Hemorrhage (30 ml/kg) decreased systemic arterial pressure from 68 ± 12 to 40 ± 10 mm Hg but did not decrease blood flow to any brain region. Indomethacin treatment (5 mg/kg) of hypotensive piglets decreased blood flow to all brain regions within 20 min; this decrease in CBF resulted from increases in cerebral vascular resistance of 65 and 281% at 20 and 40 min after treatment, respectively. In hypotensive piglets, cerebral oxygen consumption was reduced from 2.62 ± 0.71 to 0.53 ± 0.27 ml 100g−1 min−1 and to 0.11 ± 0.04 ml 100 g−1 min−1 at 20 and 40 min following indomethacin, respectively. Treatment with naloxone (1 mg/kg) had no effect on rCBF, calculated cerebral vascular resistance, or cerebral oxygen consumption of normotensive or hypotensive piglets. However, decreases in CBF and oxygen consumption and increases in cerebral vascular resistance upon treatment of hypotensive piglets with indomethacin were attenuated in animals pretreated with naloxone. These data indicate that the removal of prostanoid modulation of an opioid-mediated constrictor influence on the cerebral circulation is a potential mechanism for the increase in cerebral vascular resistance that follows indomethacin treatment of hypotensive piglets.

1990 ◽  
Vol 258 (2) ◽  
pp. H408-H413 ◽  
Author(s):  
W. M. Armstead ◽  
C. W. Leffler ◽  
D. W. Busija ◽  
R. Mirro

The interaction between vasopressinergic and prostanoid mechanisms in the control of cerebral hemodynamics in the conscious hypotensive newborn pig was investigated. Indomethacin treatment (5 mg/kg) of hypotensive piglets caused a significant decrease in blood flow to all brain regions within 20 min. This decrease in cerebral blood flow resulted from increased cerebral vascular resistances of 52 and 198% 20 and 40 min after treatment, respectively. Cerebral oxygen consumption was reduced from 2.58 +/- 0.32 ml.100 g-1.min-1 to 1.01 +/- 0.12 and 0.29 +/- 0.08 ml.100 g-1.min-1 20 and 40 min after indomethacin, respectively, in hemorrhaged piglets. Treatment with the putative vascular (V1) receptor antagonist [1-(beta-mercapto-beta, beta-cyclopentamethylene propionic acid-2-(O-methyl)tyrosine]arginine vasopressin (MEAVP) had no effect on regional cerebral blood flow, calculated cerebral vascular resistance, or cerebral metabolic rate either before or during hemorrhagic hypotension. However, decreases in cerebral blood flow and metabolic rate and increases in vascular resistance on treatment with indomethacin were blunted markedly in animals treated with MEAVP. These data are consistent with the hypothesis that the prostanoid system contributes to the maintenance of cerebral blood flow and cerebral metabolic rate during hypotension in the newborn pig, as reported previously, and implicate removal of vasopressinergic modulation by prostanoids as a potential mechanism for indomethacin-induced cerebral vasoconstriction in hypotensive newborn piglets.


Blood ◽  
1951 ◽  
Vol 6 (3) ◽  
pp. 213-227 ◽  
Author(s):  
PERITZ SCHEINBERG

Abstract 1. Cerebral blood flow and metabolism were measured in 16 patients with pernicious anemia. Seven of the patients were restudied in various stages of therapy. 2. The patients fell into two equal groups, those with severe anemia and those with moderate or no anemia. In the first group, cerebral blood flow was increased and cerebral vascular resistance decreased; in the second group, cerebal blood flow was decreased and vascular resistance increased. In both groups, cerebral oxygen and glucose consumption was decreased, as was cerebral venous oxygen tension . 3. There was a good correlation between the mental status defects and cerebral oxygen consumption and between severity of neurologic involvement and cerebral oxygen consumption. There was no correlation between cerebro-vascular resistance and cerebral oxygen consumption, nor between degree of anemia and cerebral oxygen consumption. 4. Specific therapy resulted in a moderate increase in cerebral oxygen consumption and cerebro-vascular resistance. In no instance did cerebral oxygen consumption become normal. 5. The disparity between the functional ability of the patients and the low values for cerebral metabolism is discussed. 6. It is concluded that pernicious anemia results in specific nervous system involvement not related to the anemia, and that this damage is at least partially irreversible in many patients.


1988 ◽  
Vol 254 (4) ◽  
pp. H671-H677
Author(s):  
W. M. Armstead ◽  
C. W. Leffler ◽  
D. W. Busija ◽  
D. G. Beasley ◽  
R. Mirro

The interaction between adrenergic and prostanoid mechanisms in the control of cerebral hemodynamics in the conscious, hypotensive newborn pig was investigated. Pretreatment with the selective alpha 1- and alpha 2-adrenoceptor antagonists prazosin and yohimbine, respectively, had no effect on cerebral blood flow, calculated cerebral vascular resistance, or cerebral metabolic rate either before or after hemorrhagic hypotension. Indomethacin treatment (5 mg/kg ia) of piglets following hemorrhage caused a significant decrease in blood flow to all brain regions within 20 min. This decrease in cerebral blood flow resulted from increased cerebral vascular resistances of 54 and 177%, 20 and 40 min after treatment, respectively. Cerebral oxygen consumption was reduced from 2.42 +/- 0.28 to 1.45 +/- 0.28 ml.100 g-1.min-1 and to 1.0 +/- 0.28 ml.100 g-1.min-1 20 and 40 min after indomethacin, respectively, in hemorrhaged piglets. Decreases in cerebral blood flow and metabolic rate and increases in vascular resistance on treatment with indomethacin were the same as in animals pretreated with vehicle, prazosin, or yohimbine. These data are consistent with the hypothesis that the prostanoid system contributes to the maintenance of cerebral blood flow and cerebral metabolic rate during hypotension in the newborn, as reported previously. These data do not implicate removal of sympathetic modulation by prostanoids as a mechanism for indomethacin-induced cerebral vasoconstriction in hypotensive newborn piglets.


1976 ◽  
Vol 231 (2) ◽  
pp. 489-494 ◽  
Author(s):  
ET MacKenzie ◽  
J McCulloch ◽  
AM Harper

The influence of brain norepinephrine on cerebral metabolism and blood flow was examined because exogenous norepinephrine, administered in a way that the blood-brain barrier is bypassed, has been shown to effect pronounced changes in the cerebral circulation. Reserpine (40 mug/kg, by intracarotid infusion) was administered in order to release brain norepinephrine in five anesthetized baboons. Reserpine significantly increased cerebral oxygen consumption (23%) and cerebral blood flow (50%). This response lasted for approximately 60 min. In a further five animals, effects of central beta-adrenoreceptor blockade were studied. Pro pranolol (12 mug/kg-min) produced an immediate, significant reduction in both cerebral oxygen consumption (40%) and cerebral glucose uptake (39%). Cerebral blood flow was reduced minimally. However, the responsiveness of the cerebral circulation to induced hypercapnia was severely attenuated from a gradient of 3.22 before, to 1,11 after, administration. These experiments suggest that central norepinephrine can influence the cerebral circulation primarily through noradrenergic effects on brain metabolism.


1989 ◽  
Vol 70 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Michel Pinaud ◽  
Réml Souron ◽  
Jean-Noël Lelausque ◽  
Marie-France Gazeau ◽  
Youenn Lajat ◽  
...  

Stroke ◽  
1974 ◽  
Vol 5 (6) ◽  
pp. 719-724 ◽  
Author(s):  
YOSHIHIRO KURIYAMA ◽  
TAKASHI AOYAMA ◽  
KUNIHIKO TADA ◽  
SHOTARO YONEDA ◽  
TADAATSU NUKADA ◽  
...  

1995 ◽  
Vol 7 (3) ◽  
pp. 463 ◽  
Author(s):  
GJ McCrabb ◽  
R Harding

The changes in regional cerebral blood flow (CBF) in response to prolonged hypoxaemia were measured using coloured microspheres in the 0.6-gestation ovine fetus (n = 5). Fetal hypoxaemia was induced for 12 h by reducing maternal uterine blood flow with an adjustable clamp. CBF (mL min-1 100 g-1) was increased (P < 0.05) from control values (38.7 +/- 3.5) to 105.6 +/- 5.6 at 6 h of hypoxaemia, and to 121.9 +/- 23.1 at 12 h of hypoxaemia. One hour after fetal hypoxaemia had ceased, CBF (54.0 +/- 3.3) had decreased (P < 0.05) towards control values indicating incomplete cardiovascular recovery. Cerebral vascular resistance at 6 h and 12 h of hypoxaemia was lower (P < 0.05) than control values, and returned to control values 1 h after fetal hypoxaemia had ceased. Cerebral oxygen delivery at 6 h and 12 h of hypoxaemia was not significantly different from control values, but was higher (P < 0.05) 1 h after hypoxaemia had ceased. It is concluded that CBF is sufficiently increased during prolonged hypoxaemia in the mid-gestation fetus to maintain cerebral oxygen delivery.


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