TABLE 2. MAO activity in different human tissues. Percent MAO-A and MAO-B activity are estimate, assuming 100% substrate specificity of 5-HT for MAO-A and PEA for MAO-B, respectively. Actual percentages may vary slightly. (From refs. 83,,84,,99)

Tissue

MAO

Activity

(5-HT substrate, nmol/

30min/

mg protein)

MAO

Activity

(PEA substrate,

nmol/

30min/

mg protein)

MAO-A

(% of total

activity)

MAO-B

(% of total

activity)

Brain

Hypothalamus

14.1

13.9

50

50

Cerebral Cortex

8.1

7.9

51

49

Cerebellar Cortex

2.8

1.6

63

37

Pons

8.0

8.9

47

53

Medulla Oblongata

7.1

12.6

36

64

Substantia Nigra

10.6

12.1

47

53

Caudate

7.1

12.7

36

64

Liver

92.0

33.0

74

26

Placenta

140.0

20.0

87

13

Intestine

15.0

5.0

75

25

Adrenal

33.4

10.0

77

23

Kidney

38.8

17.0

70

30

Skeletal Muscle

4.3

4.0

52

48

Heart

19.0

10.0

66

34

Lung

17.0

4.1

81

19

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published 2000