356
CHESTER JONES, CHAN, HENDEZSON, AND BALL
cells also changes with variations in the salinity of the medium (Lagios,
1968; Meyer et al., 1967; Sokabe, 1968). The existence of a macula densa
in teleosts seems doubtful since in many cases a distal tubule proper is
not present ( G r d i n , 1937).
Studies measuring renin content of kidneys of euryhaline species in
either marine or freshwater habitats or the renal content of purely stenohaline species have extended the studies of Freidman et d. (1942). Conflicting results have however been reported. Kaley and Donshik (1965)
and Kaley et al. ( 1963) reported greater amounts of renal renin in marine
species, while Sokabe et al. (1966) and Sokabe (1968) have found less
renin in seawater-adapted eels. The actual relevance of renal content of
renin is unknown, and indeed Malvin and Vander (1967) were unable to
detect changes in plasma renin activity when freshwater and marine fish
plasmas were compared.
Sokabe (1968) and Sokabe et al. (1968) have discussed the possible
role of a renin-angiotensin system in the adaptation of teleosts to different
salinities. Further study is essential before firm conclusions can be reached
as to whether renin directly influences renal function in marine and freshwater adaptation or whether the renin acts through an effect upon the
adrenocortical secretions.
Juxtaglomemlar-type cells in cyclostomes and elasmobranchs have not
been detected (Capreol and Sutherland, 1968; Bohle and Walwig, 1981).
VII. CORPUSCLES OF STANNIUS
A. Presence of Renin Activity
Extracts of the corpuscles of Stannius of the eel caused a rise in bIood
pressure in the eel which resembled that evoked by mammalian renin
(Chester Jones and Henderson, 1985; Chester Jones et al., 1966; Chan
et al., 1969; Fig. 9). In addition, incubation of corpuscular extracts with
a renin substrate resulted in the formation of a substance which caused
prolonged pressor actions in the rat. Angiotensinase is present in very
high amounts in the corpuscles of Stannius, and, recently, using procedures to block these angiotensin-degrading enzymes, it has been found
that the corpuscles of Stannius contain substantial amounts of renin activity. On a weight basis, however, it was found that the renin activity is
less in the corpuscles than in renal extracts (J. I. S. Robertson and Tree,
1988).
CHESTER JONES, CHAN, HENDEZSON, AND BALL
cells also changes with variations in the salinity of the medium (Lagios,
1968; Meyer et al., 1967; Sokabe, 1968). The existence of a macula densa
in teleosts seems doubtful since in many cases a distal tubule proper is
not present ( G r d i n , 1937).
Studies measuring renin content of kidneys of euryhaline species in
either marine or freshwater habitats or the renal content of purely stenohaline species have extended the studies of Freidman et d. (1942). Conflicting results have however been reported. Kaley and Donshik (1965)
and Kaley et al. ( 1963) reported greater amounts of renal renin in marine
species, while Sokabe et al. (1966) and Sokabe (1968) have found less
renin in seawater-adapted eels. The actual relevance of renal content of
renin is unknown, and indeed Malvin and Vander (1967) were unable to
detect changes in plasma renin activity when freshwater and marine fish
plasmas were compared.
Sokabe (1968) and Sokabe et al. (1968) have discussed the possible
role of a renin-angiotensin system in the adaptation of teleosts to different
salinities. Further study is essential before firm conclusions can be reached
as to whether renin directly influences renal function in marine and freshwater adaptation or whether the renin acts through an effect upon the
adrenocortical secretions.
Juxtaglomemlar-type cells in cyclostomes and elasmobranchs have not
been detected (Capreol and Sutherland, 1968; Bohle and Walwig, 1981).
VII. CORPUSCLES OF STANNIUS
A. Presence of Renin Activity
Extracts of the corpuscles of Stannius of the eel caused a rise in bIood
pressure in the eel which resembled that evoked by mammalian renin
(Chester Jones and Henderson, 1985; Chester Jones et al., 1966; Chan
et al., 1969; Fig. 9). In addition, incubation of corpuscular extracts with
a renin substrate resulted in the formation of a substance which caused
prolonged pressor actions in the rat. Angiotensinase is present in very
high amounts in the corpuscles of Stannius, and, recently, using procedures to block these angiotensin-degrading enzymes, it has been found
that the corpuscles of Stannius contain substantial amounts of renin activity. On a weight basis, however, it was found that the renin activity is
less in the corpuscles than in renal extracts (J. I. S. Robertson and Tree,
1988).