38
Ν. G. PON
ischemic kidney whereas those of the undamped contralateral kidney
decreased significantly (280). The change in renin content paralleled the
enzymatic changes; thus a possible relationship between the enzymatic
activity in the macula densa and renin formation was proposed. Massive
doses of deoxycorticosterone plus high saline diet administered to rats or
unilateral nephrectomy plus high saline diet decreased the G-6-P DH
kidney
(rat, G-6-P DH) (278)
I
cortex
(rat, G-6-P DH and 6-PG DH) (279)
(rabbit, G-6-P DH and 6-PG DH) (137)
glomerulus
macula densa
arteriole
(rat, G-6-P DH) (278)
(rat, G-6-P DH and
(rat, G-6-P DH) (278)
6-PG DH) (280)
FIG. 4. Distribution of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in various tissues of the kidney.
activity in the macula densa cells accompanied by a concomitant decrease in the renin content of kidney homogenate (282). On the other
hand, bilateral adrenalectomy plus a low-salt diet treatment of rats gave
a rise in G-6-P DH activity. The role of the pentose phosphate cycle in
the renin formation-enzyme activity relationship is unknown. Nephrosis,
induced by administration of an aminonucleoside of puromycin to rats,
also increased the activity of G-6-P DH in whole kidney homogenate,
glomeruli, and renal arterioles (278).
11. Liver
The amount of literature dealing with carbohydrate metabolism by
the pentose phosphate cycle in the liver is second only to that in
erythrocytes. This fact is not too surprising in view of the easy availability of this organ and in view of the extensive characterization of this
organ in terms of its physiology, anatomy, biochemistry, and pathology.
There is no question that the liver is capable of catabolizing glucose via
the shunt mechanism, various related enzymes being detected in liver
homogenates of different mammalian sources. Some examples of these
enzymes and their sources are itemized in Table III. It should be noted
that G-6-P DH in mouse or rat liver cytoplasm is the least active when
compared with enzymes involved in glycolysis, glycogenesis, glycogenosis, and gluconeogenesis (286). In fact, if glucose were utilized
under conditions where maximum rates exist, the oxidation of this sugar
medulla
(rabbit, G-6-P DH and
6-PG DH) (137)
Ν. G. PON
ischemic kidney whereas those of the undamped contralateral kidney
decreased significantly (280). The change in renin content paralleled the
enzymatic changes; thus a possible relationship between the enzymatic
activity in the macula densa and renin formation was proposed. Massive
doses of deoxycorticosterone plus high saline diet administered to rats or
unilateral nephrectomy plus high saline diet decreased the G-6-P DH
kidney
(rat, G-6-P DH) (278)
I
cortex
(rat, G-6-P DH and 6-PG DH) (279)
(rabbit, G-6-P DH and 6-PG DH) (137)
glomerulus
macula densa
arteriole
(rat, G-6-P DH) (278)
(rat, G-6-P DH and
(rat, G-6-P DH) (278)
6-PG DH) (280)
FIG. 4. Distribution of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in various tissues of the kidney.
activity in the macula densa cells accompanied by a concomitant decrease in the renin content of kidney homogenate (282). On the other
hand, bilateral adrenalectomy plus a low-salt diet treatment of rats gave
a rise in G-6-P DH activity. The role of the pentose phosphate cycle in
the renin formation-enzyme activity relationship is unknown. Nephrosis,
induced by administration of an aminonucleoside of puromycin to rats,
also increased the activity of G-6-P DH in whole kidney homogenate,
glomeruli, and renal arterioles (278).
11. Liver
The amount of literature dealing with carbohydrate metabolism by
the pentose phosphate cycle in the liver is second only to that in
erythrocytes. This fact is not too surprising in view of the easy availability of this organ and in view of the extensive characterization of this
organ in terms of its physiology, anatomy, biochemistry, and pathology.
There is no question that the liver is capable of catabolizing glucose via
the shunt mechanism, various related enzymes being detected in liver
homogenates of different mammalian sources. Some examples of these
enzymes and their sources are itemized in Table III. It should be noted
that G-6-P DH in mouse or rat liver cytoplasm is the least active when
compared with enzymes involved in glycolysis, glycogenesis, glycogenosis, and gluconeogenesis (286). In fact, if glucose were utilized
under conditions where maximum rates exist, the oxidation of this sugar
medulla
(rabbit, G-6-P DH and
6-PG DH) (137)