Mechanism of the Calorigenic Action of Catecholamines
277
4. MEESMANN, W.: Med. Welt (Stuttg.) 1778 (1965).
5. SUTHERLAND, E. W., and G. A. ROBISON: Pharmacol. Rev. 18, 145 (1966).
6. WEISS, B., J. J. DAVIS and B. B. BRODIE: Biochem. Pharmacol.15, 1553 (1966).
Discussion
SMITH:
Which were the environmental circumstances under which you measured the
metabolic rates?
STRUBELT:
I used the indifference temperature, and this in our rats was 28°C.
SMITH:
WILL found that the effect of catecholamines in raising the calorigenic activity
is most strongly elicited in an animal that is slightly if not considerably cooled.
Under your conditions the thermogenesis which you followed is undoubtedly
ascribable to non-shivering thermogenesis.
STRUBELT:
Yes, the thermogenesis recorded is not a consequence of increased activity but
rather of increased BMR.
SMITH:
Did you calculate the cardiac work?
STRUBELT:
In the rat the calorigenic effect of the cardiac work is only 2.5 % of the total
metabolic increment induced by catecholamines.
AW\!ON:
Catecholamines activate glycogenolysis with elevation of blood glucose and
lipolysis with increase of FF A, but nothing is known about whether they also
exert an influence on the further breakdown of glucose and FF A. Do you know
whether an increased glucose and FFA blood level does enhance total metabolism?
STRUBELT:
F. R. GRIFFITH (Physiol. Rev. 31, 151 (1951)) has shown that hyperglycaemia
does not increase total metabolism; I can confirm these results. As to the FFA,
there are some papers where an increase could be shown in the metabolic rate
of isolated organs-heart, liver (NESTEL, P. ]., and D. STEINBERG: ]. Lipid
Res. 4, 461 (1963)); CHALLONER, D. R., and D. STEINBERG: Amer. ]. Physiol.
210, 280 (1966)); however it is not possible to bring about such an increase in
the whole organism, too. This is probably a consequence of the high toxicity
ofFFA.
HORWITZ:
(1) Under the conditions of your experiment, does the blood lactate increase?
(2) Is the magnitude of this increase accountable for the observed calorigenesis?
STRUBELT:
An increase in the blood lactate after catecholamines has been shown by
several authors. L. LUNDHOLM (Acta physiol. scand. 19, Suppl. 67, 1949)
found a good correlation between increase in blood lactate and in total metabolism after application of adrenaline.
277
4. MEESMANN, W.: Med. Welt (Stuttg.) 1778 (1965).
5. SUTHERLAND, E. W., and G. A. ROBISON: Pharmacol. Rev. 18, 145 (1966).
6. WEISS, B., J. J. DAVIS and B. B. BRODIE: Biochem. Pharmacol.15, 1553 (1966).
Discussion
SMITH:
Which were the environmental circumstances under which you measured the
metabolic rates?
STRUBELT:
I used the indifference temperature, and this in our rats was 28°C.
SMITH:
WILL found that the effect of catecholamines in raising the calorigenic activity
is most strongly elicited in an animal that is slightly if not considerably cooled.
Under your conditions the thermogenesis which you followed is undoubtedly
ascribable to non-shivering thermogenesis.
STRUBELT:
Yes, the thermogenesis recorded is not a consequence of increased activity but
rather of increased BMR.
SMITH:
Did you calculate the cardiac work?
STRUBELT:
In the rat the calorigenic effect of the cardiac work is only 2.5 % of the total
metabolic increment induced by catecholamines.
AW\!ON:
Catecholamines activate glycogenolysis with elevation of blood glucose and
lipolysis with increase of FF A, but nothing is known about whether they also
exert an influence on the further breakdown of glucose and FF A. Do you know
whether an increased glucose and FFA blood level does enhance total metabolism?
STRUBELT:
F. R. GRIFFITH (Physiol. Rev. 31, 151 (1951)) has shown that hyperglycaemia
does not increase total metabolism; I can confirm these results. As to the FFA,
there are some papers where an increase could be shown in the metabolic rate
of isolated organs-heart, liver (NESTEL, P. ]., and D. STEINBERG: ]. Lipid
Res. 4, 461 (1963)); CHALLONER, D. R., and D. STEINBERG: Amer. ]. Physiol.
210, 280 (1966)); however it is not possible to bring about such an increase in
the whole organism, too. This is probably a consequence of the high toxicity
ofFFA.
HORWITZ:
(1) Under the conditions of your experiment, does the blood lactate increase?
(2) Is the magnitude of this increase accountable for the observed calorigenesis?
STRUBELT:
An increase in the blood lactate after catecholamines has been shown by
several authors. L. LUNDHOLM (Acta physiol. scand. 19, Suppl. 67, 1949)
found a good correlation between increase in blood lactate and in total metabolism after application of adrenaline.