Differential alteration of enzymes under hypobaria and hypoxia

Susheela, L.; Inamdar, A.R.; Ramasarma, T.

doi:10.1016/0014-5793(72)80507-6

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…The experiments described above show that tyrosine aminotransferase in the liver is induced on exposure of rats to low pressure and appears to be stabilized at a higher concentration on continued exposure. But this cannot be taken as a general stress response because other stress conditions such as hypoxia alone (Susheela et al, 1972) or shaking (Geller et al, 1964) did not bring about any change in the activity of this enzyme. Also, the nature of the change in the activity of this enzyme appears to differ from stress to stress, as discussed below.…”

Section: Discussionmentioning

confidence: 99%

Effect of environmental stress of low pressure on tyrosine aminotransferase and phenylalanine 4-hydroxylase activities in the rat

Namboodiri¹,

Ramasarma²

1975

Biochemical Journal

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1. Tyrosine aminotransferase activity in the liver increased about fourfold after 9h, on exposure of rats to stress of low pressure. 2. The phenylalanine hydroxylase activity increased about 60% on exposure for 24h or more. 3. An environmental pressure decrease of about 0.033 MN/m2 is needed to increase the activity of tyrosine aminotransferase. 4. Adrenalectomy completely abolished the increase in activity of tyrosine aminotransferase obtained on exposure to low pressure. 5. Treatment with cycloheximide or actinomycin D prevented the increase in activity of tyrosine aminotransferase. 6. Treatment with cycloheximide at the early part of exposure to stress prevented the increase in activity of phenylalanine hydroxylase obtained after 24h.

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Section: Discussionmentioning

confidence: 99%

Effect of environmental stress of low pressure on tyrosine aminotransferase and phenylalanine 4-hydroxylase activities in the rat

Namboodiri¹,

Ramasarma²

1975

Biochemical Journal

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“…cortisol (Knox & Mehler, 1951), tryptophan (Knox, 1951), drugs (Ruddon & Cohen, 1970), toxins (Szot & Murphy, 1970), psychopharmacological compounds (Nomura, 1965), salicylate (Badawy & Smith, 1971) and ethanol (Badawy & Evans, 1973). A similar effect on tryptophan pyrrolase was obtained when the animals were subjected to conditions of stress, such as immobilization (Curzon & Green, 1969), cold exposure (Sitaramam & Ramasarma, 1975a) and hypobaria (Inamdar et al, 1972), but not hypoxia (Susheela et al, 1972). The nature of these stimulations falls essentially into three categories.…”

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confidence: 93%

Stimulation of liver tryptophan pyrrolase during heat exposure

Manjunath¹,

Ramasarma²

1985

Biochemical Journal

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Exposure of rats to heat (39 +/- 1 degree C) stimulated liver tryptophan pyrrolase 2-fold between 3 and 48 h. Plasma corticosterone increased 2-fold after 1 h of heat exposure and decreased to a low value of 50% by 16 h. The effect of heat exposure on the enzyme was obtained in adrenalectomized animals. Stimulation by cortisol and tryptophan of the enzyme was also obtained in heat exposure, and the effects seemed to be additive. The concentration of tryptophan in the liver remained unchanged, and that in the plasma decreased to about 50% at 8 h exposure to heat and reverted to normal by 46 h. Simultaneous administration of noradrenaline to heat-exposed rats had no effect, whereas that of thyroxine partly prevented the stimulation of the enzyme activity. Hypothyroid conditions obtained by thyroidectomy or treatment with propylthiouracil significantly stimulated the enzyme activity. Cycloheximide treatment of heat-exposed rats did not prevent the stimulation of the enzyme activity. The results indicate that the effect of heat exposure on liver tryptophan pyrrolase is obtained, due to the accompanying hypothyroid condition, by increasing the activity of the existing protein by a mechanism possibly different from those known at present.

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Carbohydrate metabolism of goldfish (Carassius auratus L.)

Thillart

Smit

1984

J Comp Physiol B

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Differential alteration of enzymes under hypobaria and hypoxia

Cited by 6 publications

References 15 publications

Effect of environmental stress of low pressure on tyrosine aminotransferase and phenylalanine 4-hydroxylase activities in the rat

Effect of environmental stress of low pressure on tyrosine aminotransferase and phenylalanine 4-hydroxylase activities in the rat

Stimulation of liver tryptophan pyrrolase during heat exposure

Carbohydrate metabolism of goldfish (Carassius auratus L.)

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