168
D. J. RANDALL
H. Renin and Angiotensin I1
Angiotensin 11, formed by the action of renin on angiotensin I, is a
potent vasoconstrictor in mammals. Angiotension 11, injected into eels,
causes a marked increase in both dorsal and ventral aortic blood pressure,
but it has no effect on heart rate or pulse pressure. The corpuscles of
Stannius and kidney extracts, possible sources of renin in fish, also cause
a rise in blood pressure (Chan, 1967).
I. Oxytocin and Vasopressin
The neurohypophysial hormones oxytocin and vasopressin cause a
prolonged and marked rise in ventral aortic blood pressure, but they
have little effect on the dorsal aortic blood pressure in the eel. The
magnitude of the response varies with different hormones, the order of
potency is 4-serine 8-isoleucine oxytocin > oxytocin > 8-arginine oxytocin > arginine vasopressin > lysine vasopressin, with lysine vasopressin
having almost no effect on arterial blood pressure (Chan, 1967). The
action of these hormones on the circulation appears to be related to interaction between the hormones, catecholamines, and a-adrenergic receptor
sites.
J. Urophysial Extracts
Mugil urophysial extracts increase ventral and dorsal aortic blood
pressure when injected into the eel. The eel has a caudal lymph heart,
consisting of two chambers, an atrium, and a ventricle. The lymph heart
collects fluid from the lateral cutaneous and hemal lymphatic vessels
and pumps it into the caudal vein. Extracts from the eel urophysis increase the rate of beat of the caudal lymph heart (Chan, 1967).
ACKNOWLEDGMENTS
This manuscript was prepared while the author was a John Simon Guggenheim
Memorial Fellow in the Zoology Department, University of Bristol. The author would
like to thank Professor G. M. Hughes for his hospitality during this period.
REFERENCES
Augustinsson, K-B., Flnge, R., Johnels, A. G., and Ostlund, E. (1956). Histological
physiological and biochemical studies on the heart of two cyclostomes, Hagfish
( Myxine) and lamprey (Larnpetra). J. PhysioZ. (London) 131, 256-276.
Baumgarten, D., Randall, D. J., and Malyusz, M. (1969). Gas exchange versus ion
exchange across the gills of fishes. In preparation.
D. J. RANDALL
H. Renin and Angiotensin I1
Angiotensin 11, formed by the action of renin on angiotensin I, is a
potent vasoconstrictor in mammals. Angiotension 11, injected into eels,
causes a marked increase in both dorsal and ventral aortic blood pressure,
but it has no effect on heart rate or pulse pressure. The corpuscles of
Stannius and kidney extracts, possible sources of renin in fish, also cause
a rise in blood pressure (Chan, 1967).
I. Oxytocin and Vasopressin
The neurohypophysial hormones oxytocin and vasopressin cause a
prolonged and marked rise in ventral aortic blood pressure, but they
have little effect on the dorsal aortic blood pressure in the eel. The
magnitude of the response varies with different hormones, the order of
potency is 4-serine 8-isoleucine oxytocin > oxytocin > 8-arginine oxytocin > arginine vasopressin > lysine vasopressin, with lysine vasopressin
having almost no effect on arterial blood pressure (Chan, 1967). The
action of these hormones on the circulation appears to be related to interaction between the hormones, catecholamines, and a-adrenergic receptor
sites.
J. Urophysial Extracts
Mugil urophysial extracts increase ventral and dorsal aortic blood
pressure when injected into the eel. The eel has a caudal lymph heart,
consisting of two chambers, an atrium, and a ventricle. The lymph heart
collects fluid from the lateral cutaneous and hemal lymphatic vessels
and pumps it into the caudal vein. Extracts from the eel urophysis increase the rate of beat of the caudal lymph heart (Chan, 1967).
ACKNOWLEDGMENTS
This manuscript was prepared while the author was a John Simon Guggenheim
Memorial Fellow in the Zoology Department, University of Bristol. The author would
like to thank Professor G. M. Hughes for his hospitality during this period.
REFERENCES
Augustinsson, K-B., Flnge, R., Johnels, A. G., and Ostlund, E. (1956). Histological
physiological and biochemical studies on the heart of two cyclostomes, Hagfish
( Myxine) and lamprey (Larnpetra). J. PhysioZ. (London) 131, 256-276.
Baumgarten, D., Randall, D. J., and Malyusz, M. (1969). Gas exchange versus ion
exchange across the gills of fishes. In preparation.