Effects of cyclic AMP and dibutyryl cyclic AMP on cerebral hemodynamics and metabolism in the baboon YUKIO TAGASHIRA, M . D . , MASAYUKI MATSUDA, M . D . ,
KENNETH M. A. WELCH, M.D., EVA
CHABI, B.Sc.,
AND JOHN S. MEYER, M . D .
Department of Neurology, Baylor College of Medicine, and the Baylor-Methodist Center for Cerebrovascular Research, Houston, Texas Adenosine 3',5'-cyclic monophosphate (cyclic AMP) (0.5 mg/kg) was infused into the carotid artery of baboons anesthesized with sodium pentobarbital, causing a biphasic increase in cerebral blood flow (CBF) and reduction in cerebrovascular resistance (CVR) associated in each phase with stimulation of cerebral metabolism evidenced by increased cerebral oxygen consumption (CMRO~) and cerebral glucose consumption (CMRGI). Intracarotid dibutyryl cyclic AMP (0.5 mg/kg) caused a monophasic increase in CBF and reduction of CVR but failed to alter cerebral metabolism. This may be due to its rapid removal from the circulation with ineffective passage across the blood-brain barrier since intracisternal infusion of dibutyryl cyclic AMP caused sustained increase in CBF, CMRO~ and CMRGI and reduction in CVR. Intracarotid AMP (0.4 mg/kg) and adenosine (0.3 mg/kg) caused an immediate and more marked increase in CBF and decrease in CVR unassociated with cerebral metabolic change making it unlikely that the observed effects of cyclic AMP can be attributed to its breakdown products. Cyclic AMP or its dibutyryl derivative may alter cerebral metabolism secondary to neuronal activation but increase in glucose/oxygen utilization ratio after intracarotid cyclic AMP and intracisternal dibutyryl cyclic AMP also suggests an influence on enzymatic regulation of glucose metabolism. KEY WORDS cerebral vasodilatation 9 metabolic change blood-brain barrier 9 adenosine 9 adenosine monophosphate "
A
DENOSINE 3',5'-cyclic m o n o p h o s p h a t e (cyclic A M P ) has been implicated as the intracellular mediator for a variety of extracellular neurohumoral influences in m a m m a l i a n and n o n - m a m m a l i a n organisms, xe,~7 M a m m a l i a n brain has a great capacity for f o r m a t i o n of cyclic A M P , the activity of the synthetic enzyme, adenyl cyclase, and the catabolizing enzyme, cyclic A M P phosphodiesterase, being much higher in the central nervous system ( C N S ) than in most other body tissues? as Extensive in vitro 484
9
studies supported by limited studies in vivo have provided strong evidence that cyclic A M P plays a part in central and peripheral neurotransmission and probably plays some role in control of cerebral energy metabolism. 13 There has also been considerable interest in the possible role of cyclic A M P in v a s o m o t o r control? ,~Sa~ Evidence exists that alteration in the vascular tonus of systemic vascular beds m a y be due to stimulation of r e c e p t o r sites by b o t h n e u r o g e n i c and humoral influences, the effects of which are
J. Neurosurg. / Volume 46/April, 1977
Cyclic AMP and cerebral circulation apparently mediated by changes in intracellular cyclic A M P levels in the smooth muscle of the vessel wall. This paper reports measurements of the influence of exogenous cyclic A M P on cerebral hemodynamics and energy metabolism in vivo which hitherto have not been studied extensively in either primates or man. Materials and Methods
Preparation o f Material Thirty-four adult baboons (Papio anubis) weighing 3.5 to 13 kg were anesthetized with intravenous pentobarbital 25 mg/kg body weight. Supplemental pentobarbital was given when required. After tracheostomy animals were immobilized with gallamine triethiodide (Flaxedil) 1 mg/kg body weight. Respiration with room air was maintained by a Harvard variable speed respirator.* End expiratory CO2 was monitored by a Beckman infrared gas analyzert and maintained at 3.5% to 4.5% in each animal (corresponding to PaCO2 of 33 to 45 mm Hg) by adjusting the rate and stroke volume of the respirator. The left femoral artery and vein were exposed and polyethylene catheters introduced into both vessels. Arterial blood pressure was recorded continuously from the descending aorta by means of a Statham pressure transducerS: connected to the femoral artery catheter. The venous catheter permitted intravenous infusion of drugs or fluids as required. The extracranial vessels of the left and right side were exposed through a midline cervical incision. A thin polyethylene catheter was inserted into the right lingual artery to permit infusion of drugs to be tested. Otherwise, both external carotid arteries and branches were ligated bilaterally, together with the external jugular veins. The sympathetic and vagus nerves were carefully preserved, and special care was taken during
the entire operation to avoid excessive blood loss. Two electromagnetic flow probes connected to flow metersw were placed around both internal jugular veins, and cerebral blood flow (CBF) was continuously monitored as total cerebral venous outflow. In six animals a laminectomy was performed at T1-2 and a thin polyethylene (PE 10) catheter was inserted in a cephalad direction through a perforation in the dura into the cisterna magna to permit infusion of the drugs to be tested. The thoracic laminectomy was performed to avoid any possibility of brain-stem trauma or cerebrospinal fluid (CSF) leakage that might occur from direct cisternal puncture. The perforation in the dura and the bone defects were sealed with Oxycel, and the muscle and skin incisions were sutured to prevent any leakage of spinal fluid. The catheter was fixed in place by inclusion in the suture line. A catheter was wedged into the anterior third of the superior sagittal sinus through a midline frontal burr hole and connected to a pressure transducerll t o measure superior sagittal sinus wedge pressure (SSSP). Another catheter was inserted into the sinus confluence through a second midline burr hole to permit cerebral venous blood sampling. For this purpose the animals were heparinized and sagittal sinus blood, together with blood sampled from the right brachial artery, was pumped at a rate of 5 ml/min by means of a Harvard Sigma pump through a Guyton oxygen analyzer* in order to monitor cerebral arteriovenous oxygen differences continuously. This blood was then returned to the body through a catheter placed in the right femoral vein. Samples of arterial and cerebral venous blood were also drawn into two Technicon autoanalyzer systemst (0.05
~4-channel pulsed logic blood flowmeter system, BL-610-4B manufactured by Biotronex Laboratory, Inc., 9153 Brookville Road, Silver Spring, Maryland 20910. IIP23AC pressure transducer manufactured by *Variable speed respirator manufactured by Harvard Apparatus, Inc., 150 Dover Road, Millis, Statham Laboratories, Inc., Hato Rey, Puerto Rico 00191. Massachusetts 02054. *Guyton oxygen analyzer manufactured by Ox"l'Infrared gas analyzer manufactured by Beckman Instruments, Inc., 2500 Harbor Boulevard, ford Instrument Company, 234 Meadow Road, Jackson, Mississippi. Fullerton, California 92634. tAutoanalyzer dialyzer manufactured by :I:P231A pressure transducer manufactured by Statham Laboratories, Inc., Hato Rey, Puerto Technicon Instrument Corp., Tarrytown, New York 10591. Rico 00191.
J. Neurosurg. / Volume 46 / April, 1977
485
,.q "4
4~
oo o,
A
A
A
A
A
101.4
2.49 -4- 0.71
2.84-'-
3.93 4-
1.52 •
MABP (N--9)
CVR ( N = 9)
CMRO2 ( N = 9)
CMRG1 ( N = 6)
G/O ( N = 6)
0.6 0.0
• 10.1 :~ 3.2
:~ 10.0 -'- 3.8w
• ~
1.86 -'- 0.45 0.34 -'- 0.27w
5.06 "4- 1.72 1.13 "- 0.62w
3.09-'- 0.58 0.25 -'- 0.22w
2.30 :~ 0.74 - 0 . 1 9 :~ 0.15w
100.5 -0.8
39.7 3.4
4.0 0.0
0~ 0.6 0.0
• ~-
1.70 -'- 0.46 0.18 • 0.14
4.47 -'- 1.93 0.53 -'- 0.70w
2.89 ~ 0.73 0.04 "4- 0.30
0.87 0.21
9.7 5.7
"4- 11.9 • 8.0
• ~
2.43 • --0.06 •
100.0 -1.4
38.5 1.9
4.0 0.0
5 0.6 0.1
1.63 ~ 0.11 ~
4.78 ~0.84 •
3.04 • 0.20 •
0.55 0.29
2.17 1.04
0.68 0.50
0.75 0.33
-4-13.1 ~ 7.7
~ 12.4 ~ 8.0
~ ~
2.26 ~ -0.23 •
103.4 2.0
42.0 5.6
4.0 0.0
10
13.0 9.5w
0.6 0.1
~ 14.6 • 11.4
• •
~ •
1.57 -4- 0.38 0.05 • 0.28
4.58 -'- 1.95 0.65 ~- 0.70w
3.10 4- 0.72 0.26 ~- 0.50w
2.14 -4- 0.64 --0.35 • 0.37w
105.3 3.8
44.9 8.5
4.0 0.0
15
Time Interval After Infusion (min)
0.6 0.1
1.80 "4- 0.60 0.28 -4- 0.69
1.58 1.14
3.09 "4- 0.64 0.24 ~- 0.41w 4.72 • 0.79 •
95.7 --5.0
47.1 10.7
4.0 0.0
0.6 0.1
-'-11.7 ~-11.2
-'- 12.7 • 9.3
~ ~
45
1.79 ~ 0.27 •
4.63 "0.70 -'-
0.79 0.82
2.28 1.80
2.91 • 0.50 0.06 -4- 0.24
0.59 1.80 -'- 0.51 0.3611 - 0 . 6 9 • 0.43
"4-12.3 • 8.9
:~ 12.0 -~ 8.711
~ •
1.84 • --0.65 :~
101.8 0.4
49.1 12.7
4.1 0.0
30
*Values = m e a n -~ standard deviation, ( - ) sign denotes decrease; significant difference for A value (steady state) c o m p a r e d to A for saline g r o u p : w = p
KENNETH M. A. WELCH, M.D., EVA
CHABI, B.Sc.,
AND JOHN S. MEYER, M . D .
Department of Neurology, Baylor College of Medicine, and the Baylor-Methodist Center for Cerebrovascular Research, Houston, Texas Adenosine 3',5'-cyclic monophosphate (cyclic AMP) (0.5 mg/kg) was infused into the carotid artery of baboons anesthesized with sodium pentobarbital, causing a biphasic increase in cerebral blood flow (CBF) and reduction in cerebrovascular resistance (CVR) associated in each phase with stimulation of cerebral metabolism evidenced by increased cerebral oxygen consumption (CMRO~) and cerebral glucose consumption (CMRGI). Intracarotid dibutyryl cyclic AMP (0.5 mg/kg) caused a monophasic increase in CBF and reduction of CVR but failed to alter cerebral metabolism. This may be due to its rapid removal from the circulation with ineffective passage across the blood-brain barrier since intracisternal infusion of dibutyryl cyclic AMP caused sustained increase in CBF, CMRO~ and CMRGI and reduction in CVR. Intracarotid AMP (0.4 mg/kg) and adenosine (0.3 mg/kg) caused an immediate and more marked increase in CBF and decrease in CVR unassociated with cerebral metabolic change making it unlikely that the observed effects of cyclic AMP can be attributed to its breakdown products. Cyclic AMP or its dibutyryl derivative may alter cerebral metabolism secondary to neuronal activation but increase in glucose/oxygen utilization ratio after intracarotid cyclic AMP and intracisternal dibutyryl cyclic AMP also suggests an influence on enzymatic regulation of glucose metabolism. KEY WORDS cerebral vasodilatation 9 metabolic change blood-brain barrier 9 adenosine 9 adenosine monophosphate "
A
DENOSINE 3',5'-cyclic m o n o p h o s p h a t e (cyclic A M P ) has been implicated as the intracellular mediator for a variety of extracellular neurohumoral influences in m a m m a l i a n and n o n - m a m m a l i a n organisms, xe,~7 M a m m a l i a n brain has a great capacity for f o r m a t i o n of cyclic A M P , the activity of the synthetic enzyme, adenyl cyclase, and the catabolizing enzyme, cyclic A M P phosphodiesterase, being much higher in the central nervous system ( C N S ) than in most other body tissues? as Extensive in vitro 484
9
studies supported by limited studies in vivo have provided strong evidence that cyclic A M P plays a part in central and peripheral neurotransmission and probably plays some role in control of cerebral energy metabolism. 13 There has also been considerable interest in the possible role of cyclic A M P in v a s o m o t o r control? ,~Sa~ Evidence exists that alteration in the vascular tonus of systemic vascular beds m a y be due to stimulation of r e c e p t o r sites by b o t h n e u r o g e n i c and humoral influences, the effects of which are
J. Neurosurg. / Volume 46/April, 1977
Cyclic AMP and cerebral circulation apparently mediated by changes in intracellular cyclic A M P levels in the smooth muscle of the vessel wall. This paper reports measurements of the influence of exogenous cyclic A M P on cerebral hemodynamics and energy metabolism in vivo which hitherto have not been studied extensively in either primates or man. Materials and Methods
Preparation o f Material Thirty-four adult baboons (Papio anubis) weighing 3.5 to 13 kg were anesthetized with intravenous pentobarbital 25 mg/kg body weight. Supplemental pentobarbital was given when required. After tracheostomy animals were immobilized with gallamine triethiodide (Flaxedil) 1 mg/kg body weight. Respiration with room air was maintained by a Harvard variable speed respirator.* End expiratory CO2 was monitored by a Beckman infrared gas analyzert and maintained at 3.5% to 4.5% in each animal (corresponding to PaCO2 of 33 to 45 mm Hg) by adjusting the rate and stroke volume of the respirator. The left femoral artery and vein were exposed and polyethylene catheters introduced into both vessels. Arterial blood pressure was recorded continuously from the descending aorta by means of a Statham pressure transducerS: connected to the femoral artery catheter. The venous catheter permitted intravenous infusion of drugs or fluids as required. The extracranial vessels of the left and right side were exposed through a midline cervical incision. A thin polyethylene catheter was inserted into the right lingual artery to permit infusion of drugs to be tested. Otherwise, both external carotid arteries and branches were ligated bilaterally, together with the external jugular veins. The sympathetic and vagus nerves were carefully preserved, and special care was taken during
the entire operation to avoid excessive blood loss. Two electromagnetic flow probes connected to flow metersw were placed around both internal jugular veins, and cerebral blood flow (CBF) was continuously monitored as total cerebral venous outflow. In six animals a laminectomy was performed at T1-2 and a thin polyethylene (PE 10) catheter was inserted in a cephalad direction through a perforation in the dura into the cisterna magna to permit infusion of the drugs to be tested. The thoracic laminectomy was performed to avoid any possibility of brain-stem trauma or cerebrospinal fluid (CSF) leakage that might occur from direct cisternal puncture. The perforation in the dura and the bone defects were sealed with Oxycel, and the muscle and skin incisions were sutured to prevent any leakage of spinal fluid. The catheter was fixed in place by inclusion in the suture line. A catheter was wedged into the anterior third of the superior sagittal sinus through a midline frontal burr hole and connected to a pressure transducerll t o measure superior sagittal sinus wedge pressure (SSSP). Another catheter was inserted into the sinus confluence through a second midline burr hole to permit cerebral venous blood sampling. For this purpose the animals were heparinized and sagittal sinus blood, together with blood sampled from the right brachial artery, was pumped at a rate of 5 ml/min by means of a Harvard Sigma pump through a Guyton oxygen analyzer* in order to monitor cerebral arteriovenous oxygen differences continuously. This blood was then returned to the body through a catheter placed in the right femoral vein. Samples of arterial and cerebral venous blood were also drawn into two Technicon autoanalyzer systemst (0.05
~4-channel pulsed logic blood flowmeter system, BL-610-4B manufactured by Biotronex Laboratory, Inc., 9153 Brookville Road, Silver Spring, Maryland 20910. IIP23AC pressure transducer manufactured by *Variable speed respirator manufactured by Harvard Apparatus, Inc., 150 Dover Road, Millis, Statham Laboratories, Inc., Hato Rey, Puerto Rico 00191. Massachusetts 02054. *Guyton oxygen analyzer manufactured by Ox"l'Infrared gas analyzer manufactured by Beckman Instruments, Inc., 2500 Harbor Boulevard, ford Instrument Company, 234 Meadow Road, Jackson, Mississippi. Fullerton, California 92634. tAutoanalyzer dialyzer manufactured by :I:P231A pressure transducer manufactured by Statham Laboratories, Inc., Hato Rey, Puerto Technicon Instrument Corp., Tarrytown, New York 10591. Rico 00191.
J. Neurosurg. / Volume 46 / April, 1977
485
,.q "4
4~
oo o,
A
A
A
A
A
101.4
2.49 -4- 0.71
2.84-'-
3.93 4-
1.52 •
MABP (N--9)
CVR ( N = 9)
CMRO2 ( N = 9)
CMRG1 ( N = 6)
G/O ( N = 6)
0.6 0.0
• 10.1 :~ 3.2
:~ 10.0 -'- 3.8w
• ~
1.86 -'- 0.45 0.34 -'- 0.27w
5.06 "4- 1.72 1.13 "- 0.62w
3.09-'- 0.58 0.25 -'- 0.22w
2.30 :~ 0.74 - 0 . 1 9 :~ 0.15w
100.5 -0.8
39.7 3.4
4.0 0.0
0~ 0.6 0.0
• ~-
1.70 -'- 0.46 0.18 • 0.14
4.47 -'- 1.93 0.53 -'- 0.70w
2.89 ~ 0.73 0.04 "4- 0.30
0.87 0.21
9.7 5.7
"4- 11.9 • 8.0
• ~
2.43 • --0.06 •
100.0 -1.4
38.5 1.9
4.0 0.0
5 0.6 0.1
1.63 ~ 0.11 ~
4.78 ~0.84 •
3.04 • 0.20 •
0.55 0.29
2.17 1.04
0.68 0.50
0.75 0.33
-4-13.1 ~ 7.7
~ 12.4 ~ 8.0
~ ~
2.26 ~ -0.23 •
103.4 2.0
42.0 5.6
4.0 0.0
10
13.0 9.5w
0.6 0.1
~ 14.6 • 11.4
• •
~ •
1.57 -4- 0.38 0.05 • 0.28
4.58 -'- 1.95 0.65 ~- 0.70w
3.10 4- 0.72 0.26 ~- 0.50w
2.14 -4- 0.64 --0.35 • 0.37w
105.3 3.8
44.9 8.5
4.0 0.0
15
Time Interval After Infusion (min)
0.6 0.1
1.80 "4- 0.60 0.28 -4- 0.69
1.58 1.14
3.09 "4- 0.64 0.24 ~- 0.41w 4.72 • 0.79 •
95.7 --5.0
47.1 10.7
4.0 0.0
0.6 0.1
-'-11.7 ~-11.2
-'- 12.7 • 9.3
~ ~
45
1.79 ~ 0.27 •
4.63 "0.70 -'-
0.79 0.82
2.28 1.80
2.91 • 0.50 0.06 -4- 0.24
0.59 1.80 -'- 0.51 0.3611 - 0 . 6 9 • 0.43
"4-12.3 • 8.9
:~ 12.0 -~ 8.711
~ •
1.84 • --0.65 :~
101.8 0.4
49.1 12.7
4.1 0.0
30
*Values = m e a n -~ standard deviation, ( - ) sign denotes decrease; significant difference for A value (steady state) c o m p a r e d to A for saline g r o u p : w = p
