Effect of autonomic agents on renin release in the turtle, XXXX .

@entity1169 @entity1425 @entity5333 @entity8308 @entity1617 @entity3897 @entity3044 @entity2661 @entity1063 @entity934
Experiments were conducted in the freshwater turtle, @entity8308 , to study the effect of autonomic agents on the control of renin in this primitive species. The unique finding in these studies was that, unlike mammals, @entity3044 infusion fails to increase renin activity even though heart rate and arterial pressure patterns indicated that systemic responses were similar to that in mammals. On the other hand, @entity934 ( @entity1617 ) infusion resulted in a prompt threefold elevation (P less than 0.01) of renin activity. This response was blocked by @entity1169 but not @entity3897 . Other experiments demonstrated that @entity1617 elicited a prompt elevation of circulating @entity1063 and @entity1425 in these turtles and led to the hypothesis that the renin response to @entity1617 was secondary to the release of endogenous @entity2661 . This hypothesis was supported by the fact that, in reserpinized turtles, @entity1617 failed to elicit the usual renin response. Further evidence stemmed from the fact that @entity1425 administration led to a prompt fourfold increase (P less than 0.01) in renin, which could be blocked by @entity1169 . On the other hand, @entity5333 failed to block the response under identical conditions. Taken as a whole, these data suggest that in this primitive species renin activity is elevated by endogenous @entity2661 even though @entity3044 , a classical beta-adrenergic agonist, is without effect. These data illustrate again the need for caution when assuming analogy when comparing responses in primitive species with that of mammals.
