scholarly journals Astrocytes monitor cerebral perfusion and control systemic circulation to maintain brain blood flow

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nephtali Marina ◽  
Isabel N. Christie ◽  
Alla Korsak ◽  
Maxim Doronin ◽  
Alexey Brazhe ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Cerebral Perfusion ◽  
Brain Perfusion ◽  
Brain Blood Flow ◽  
Sympathetic Control ◽  
Arterial Blood ◽  
Control Circuits

AbstractAstrocytes provide neurons with essential metabolic and structural support, modulate neuronal circuit activity and may also function as versatile surveyors of brain milieu, tuned to sense conditions of potential metabolic insufficiency. Here we show that astrocytes detect falling cerebral perfusion pressure and activate CNS autonomic sympathetic control circuits to increase systemic arterial blood pressure and heart rate with the purpose of maintaining brain blood flow and oxygen delivery. Studies conducted in experimental animals (laboratory rats) show that astrocytes respond to acute decreases in brain perfusion with elevations in intracellular [Ca2+]. Blockade of Ca2+-dependent signaling mechanisms in populations of astrocytes that reside alongside CNS sympathetic control circuits prevents compensatory increases in sympathetic nerve activity, heart rate and arterial blood pressure induced by reductions in cerebral perfusion. These data suggest that astrocytes function as intracranial baroreceptors and play an important role in homeostatic control of arterial blood pressure and brain blood flow.

Effects of l-arginine on systemic and renal haemodynamics in conscious dogs

1991 ◽  
Vol 81 (6) ◽  
pp. 727-732 ◽  
Author(s):  
Marohito Murakami ◽  
Hiromichi Suzuki ◽  
Atsuhiro Ichihara ◽  
Mareo Naitoh ◽  
Hidetomo Nakamoto ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Renal Haemodynamics ◽  
Conscious Dogs ◽  
Arginine Infusion ◽  
Arterial Blood

1. The effects of l-arginine on systemic and renal haemodynamics were investigated in conscious dogs. l-Arginine was administered intravenously at doses of 15 and 75 μmol min−1 kg−1 for 20 min. 2. Mean arterial blood pressure, heart rate and cardiac output were not changed significantly by l-arginine infusion. However, l-arginine infusion induced a significant elevation of renal blood flow from 50 ± 3 to 94 ± 12 ml/min (means ± sem, P < 0.01). 3. Simultaneous infusion of NG-monomethyl-l-arginine (0.5 μmol min−1 kg−1) significantly inhibited the increase in renal blood flow produced by l-arginine (15 μmol min−1 kg−1) without significant changes in mean arterial blood pressure or heart rate. 4. Pretreatment with atropine completely inhibited the l-arginine-induced increase in renal blood flow, whereas pretreatment with indomethacin attenuated it (63 ± 4 versus 82 ± 10 ml/min, P < 0.05). 5. A continuous infusion of l-arginine increased renal blood flow in the intact kidney (55 ± 3 versus 85 ± 9 ml/min, P < 0.05), but not in the contralateral denervated kidney (58 ± 3 versus 56 ± 4 ml/min, P > 0.05). 6. These results suggest that intravenously administered l-arginine produces an elevation of renal blood flow, which may be mediated by facilitation of endogenous acetylcholine-induced release of endothelium-derived relaxing factor and vasodilatory prostaglandins.

Patterned cardiovascular responses to sleep and nonrespiratory arousals in a porcine model

1998 ◽  
Vol 85 (4) ◽  
pp. 1285-1291 ◽  
Author(s):  
Sandrine H. Launois ◽  
Joseph H. Abraham ◽  
J. Woodrow Weiss ◽  
Debra A. Kirby
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Eye Movement ◽  
Arterial Blood Pressure ◽  
Vascular Resistance ◽  
Mean Arterial Blood Pressure ◽  
Rapid Eye Movement ◽  
Rapid Eye Movement Sleep ◽  
Arterial Blood

Patients with obstructive sleep apnea experience marked cardiovascular changes with apnea termination. Based on this observation, we hypothesized that sudden sleep disruption is accompanied by a specific, patterned hemodynamic response, similar to the cardiovascular defense reaction. To test this hypothesis, we recorded mean arterial blood pressure, heart rate, iliac blood flow and vascular resistance, and renal blood flow and vascular resistance in five pigs instrumented with chronic sleep electrodes. Cardiovascular parameters were recorded during quiet wakefulness, during non-rapid-eye-movement and rapid-eye-movement sleep, and during spontaneous and induced arousals. Iliac vasodilation (iliac vascular resistance decreased by −29.6 ± 4.1% of baseline) associated with renal vasoconstriction (renal vascular resistance increased by 10.3 ± 4.0%), tachycardia (heart rate increase: +23.8 ± 3.1%), and minimal changes in mean arterial blood pressure were the most common pattern of arousal response, but other hemodynamic patterns were observed. Similar findings were obtained in rapid-eye-movement sleep and for acoustic and tactile arousals. In conclusion, spontaneous and induced arousals from sleep may be associated with simultaneous visceral vasoconstriction and hindlimb vasodilation, but the response is variable.

Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

1991 ◽  
Vol 261 (4) ◽  
pp. H982-H988
Author(s):  
J. H. Sindrup ◽  
J. Kastrup ◽  
H. Christensen ◽  
B. Jorgensen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Flow Rate ◽  
Mean Arterial Blood Pressure ◽  
Blood Flow Rate ◽  
Tissue Blood Flow ◽  
Peripheral Blood Flow ◽  
Arterial Blood

Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease in mean arterial blood pressure (P less than 0.001) were observed. The duration of this hyperemic phase was 116 min. A highly significant reduction of the subcutaneous vascular resistance (50%) was demonstrated during the hyperemic blood flow rate phase compared with the surrounding phases (P less than 0.0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.

Cerebral blood flow and behavior during brain stimulation in the goat

1977 ◽  
Vol 232 (5) ◽  
pp. H495-H499
Author(s):  
M. Manrique ◽  
E. Alborch ◽  
J. M. Delgado
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood Pressure ◽  
Maxillary Artery ◽  
Internal Maxillary Artery ◽  
Arterial Blood ◽  
And Behavior ◽  
Stimulation Of

Cerebral blood flow, heart rate, arterial blood pressure, and behavior were studied in conscious goats during electrical stimulation of the diencephalon and mesencephalon. Stimulation of the subthalamic area produced a considerable increase in ipsilateral cerebral blood flow and heart rate, accompanied by either a small or a large increase in systemic arterial blood pressure. Cardiovascular effects were associated with changes in alertness. The increase in cerebral blood flow was partially abolished by previous administration of atropine directly into the internal maxillary artery. Stimulation of the mesencephalic reticular formation caused a marked increase in blood pressure with no change or with some decrease in cerebral blood flow. After administration of phentolamine into the internal maxillary artery, stimulation produced increase in cerebral blood flow. The behavioral response consisted of restlessness and attempted flight. These results suggest the existence of cholinergic vasodilator and adrenergic vasoconstrictor pathways to cerebral blood vessels that may be stimulated electrically.

Effect of intravenous infusion of adrenaline on the cardiovascular responses to distal body subatmospheric pressure in man

1988 ◽  
Vol 75 (4) ◽  
pp. 389-394 ◽  
Author(s):  
I. W. Fellows ◽  
I. A. MacDonald ◽  
T. Bennett ◽  
D. P. O'Donoghue
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Forearm Blood Flow ◽  
Cardiovascular Responses ◽  
Saline Infusion ◽  
Subatmospheric Pressure ◽  
Arterial Blood ◽  
Adrenaline Infusion

1. On two separate occasions, at least 1 week apart, seven young healthy male subjects received intravenous infusions of either adrenaline [0.27 nmol (50 ng) min−1 kg−1] or saline (154 mmol/l NaCl), plus ascorbic acid (5.68 mmol/l), over 30 min. 2. On each occasion, the subjects were exposed to distal body subatmospheric pressure (DBSP), 0 to 50 mmHg (0 to 6.65 kPa) in 10 mmHg (1.33 kPa) steps, before infusion, during the final 15 min of the infusion, and at 15 min and 30 min after the cessation of the infusion. 3. Venous adrenaline concentrations of 2.85 ±0.22 nmol/l were achieved during the adrenaline infusion, compared with 0.49 ± 0.07 nmol/l during the saline infusion (P < 0.001). At 15 min and at 30 min after cessation of the adrenaline infusion, venous adrenaline concentrations had fallen to levels similar to those achieved after the cessation of the saline infusion. 4. Heart rate rose significantly from 58 ±4 beats/min to 67 ±4 beats/min during the adrenaline infusion (P < 0.05), but there was no further significant change in response to 50 mmHg (6.65 kPa) DBSP. At 30 min after the cessation of the adrenaline infusion, heart rate rose from 60 ± 4 beats/min to 78 ± 7 beats/min in response to 50 mmHg DBSP. This increase was significantly greater than that observed before the adrenaline infusion [58 ± 4 beats/min to 69 ±7 beats/min during 50 mmHg (6.65 kPa) DBSP; P < 0.01]. 5. During the infusion of adrenaline, systolic arterial blood pressure rose and diastolic arterial blood pressure fell, but the blood pressure responses to DBSP were unaffected. 6. Forearm blood flow increased significantly during adrenaline infusion but there was no significant difference in the fall in forearm blood flow during DBSP compared with the values before infusion. At 15 min after the cessation of the adrenaline infusion, forearm vascular resistance rose proportionately more in response to DBSP than it had before the adrenaline infusion (P < 0.05). 7. These results are consistent with adrenaline-mediated facilitation of sympathetic neuronal release of noradrenaline in the heart and in the forearm vascular bed.

Circadian periodicity of cerebral blood flow revealed by laser-Doppler flowmetry in awake rats: relation to blood pressure and activity

2005 ◽  
Vol 289 (4) ◽  
pp. H1662-H1668 ◽  
Author(s):  
C. A. Wauschkuhn ◽  
K. Witte ◽  
S. Gorbey ◽  
B. Lemmer ◽  
L. Schilling
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Locomotor Activity ◽  
Cerebral Perfusion ◽  
Circadian Variation ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Circadian Periodicity ◽  
Arterial Blood

Cardiovascular parameters such as arterial blood pressure (ABP) and heart rate display pronounced circadian variation. The present study was performed to detect whether there is a circadian periodicity in the regulation of cerebral perfusion. Normotensive Sprague-Dawley rats (SDR, ∼15 wk old) and hypertensive (mREN2)27 transgenic rats (TGR, ∼12 wk old) were instrumented in the abdominal aorta with a blood pressure sensor coupled to a telemetry system for continuous recording of ABP, heart rate, and locomotor activity. After 5–12 days, a laser-Doppler flow (LDF) probe was attached to the skull by means of a guiding device to measure changes in brain cortical blood flow (CBF). After the animals recovered from anesthesia, measurements were taken for 3–4 days. The time series were analyzed with respect to the midline estimating statistic of rhythm (i.e., mean value of a periodic event after fit to a cosine function), amplitude, and acrophase (i.e., phase angle that corresponds to the peak of a given period) of the 24-h period. The LDF signal displayed a significant circadian rhythm, with the peak occurring at around midnight in SDR and TGR, despite inverse periodicity of ABP in TGR. This finding suggests independence of LDF periodicity from ABP regulation. Furthermore, the acrophase of the LDF was consistently found before the acrophase of the activity. From the present data, it is concluded that there is a circadian periodicity in the regulation of cerebral perfusion that is independent of circadian changes in ABP and probably is also independent of locomotor activity. The presence of a circadian periodicity in CBF may have implications for the occurrence of diurnal alterations in cerebrovascular events in humans.

Cerebral Hemodynamic Effects of Morphine and Fentanyl in Patients with Severe Head Injury

2000 ◽  
Vol 92 (1) ◽  
pp. 11-11 ◽  
Author(s):  
Miriam de Nadal ◽  
Francisca Munar ◽  
M. Antonia Poca ◽  
Joan Sahuquillo ◽  
Angel Garnacho ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Intracranial Pressure ◽  
Arterial Blood Pressure ◽  
Oxygen Content ◽  
Mean Arterial Blood Pressure ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Content Difference ◽  
Arterial Blood

Background The current study investigates the effects of morphine and fentanyl upon intracranial pressure and cerebral blood flow estimated by cerebral arteriovenous oxygen content difference and transcranial Doppler sonography in 30 consecutive patients with severe head injury in whom cerebrovascular autoregulation previously had been assessed. Methods Patients received morphine (0.2 mg/kg) and fentanyl (2 microg/kg) intravenously over 1 min but 24 h apart in a randomized fashion. Before study, carbon dioxide reactivity and autoregulation were assessed. Intracranial pressure, mean arterial blood pressure, and cerebral perfusion pressure were repeatedly monitored for 1 h after the administration of both opioids. Cerebral blood flow was estimated from the reciprocal of arteriovenous oxygen content difference and middle cerebral artery mean flow velocity using transcranial Doppler sonography. Results Although carbon dioxide reactivity was preserved in all patients, 18 patients (56.7%) showed impaired or abolished autoregulation to hypertensive challenge, and only 12 (43.3%) had preserved autoregulation. Both morphine and fentanyl caused significant increases in intracranial pressure and decreases in mean arterial blood pressure and cerebral perfusion pressure, but estimated cerebral blood flow remain unchanged. In patients with preserved autoregulation, opioid-induced intracranial pressure increases were not different than in those with impaired autoregulation. Conclusions The authors conclude that both morphine and fentanyl moderately increase intracranial pressure and decrease mean arterial blood pressure and cerebral perfusion pressure but have no significant effect on arteriovenous oxygen content difference and middle cerebral artery mean flow velocity in patients with severe brain injury. No differences on intracranial pressure changes were found between patients with preserved and impaired autoregulation. Our results suggest that other mechanisms, besides the activation of the vasodilatory cascade, also could be implicated in the intracranial pressure increases seen after opioid administration.

Response of human cerebral blood flow to +Gz accelerations

1994 ◽  
Vol 76 (5) ◽  
pp. 2114-2118 ◽  
Author(s):  
G. Ossard ◽  
J. M. Clere ◽  
M. Kerguelen ◽  
F. Melchior ◽  
J. Seylaz
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood Pressure ◽  
Transcranial Doppler ◽  
Cerebral Circulation ◽  
Cerebral Perfusion ◽  
Protective Mechanisms ◽  
Arterial Blood ◽  
Onset Rate

Intolerance symptoms associated with high sustained +Gz (head to foot) accelerations are attributed to lack of cerebral perfusion. To determine the response of cerebral circulation to +Gz stress, cerebral blood flow (CBF) was measured in humans with the transcranial Doppler method while cephalic arterial blood pressure was calculated simultaneously using a photoplethysmographic technique. Nine volunteers performed four randomized centrifuge runs at +2 to +5 Gz with a 0.4-G/s onset rate for 30 s. Compared with the control values, for +2-, +3-, +4-, and +5-Gz profiles, CBF was reduced by 19 +/- 7, 26 +/- 8, 49 +/- 26, and 61 +/- 29% (SD), respectively, at the end of the onset and by 18 +/- 4, 21 +/- 11, 27 +/- 7, and 47 +/- 29%, respectively, in the last 20 s of the plateau of acceleration. At the end of the onset and during the plateau of +Gz acceleration, CBF was less reduced than cephalic arterial blood pressure, suggesting that some mechanisms would occur to maintain cerebral perfusion under +Gz stress. These protective mechanisms are likely due to a siphon effect and/or an autoregulatory compensation.

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