Temperature sensitivity of renin-angiotensin system in the ground squirrel

The alteration of renin release by alpha- and beta-adrenoceptors located on the juxtaglomerular cells has been shown to be temperature sensitive in nonhibernating mammals. These experiments investigate the effects of temperature on renin secretion by cortical slices of kidneys from the thirteen-lined ground squirrel Spermophilus tridecemlineatus. At 37 degrees C, beta-stimulation (isoproterenol 10(-7) M) increased the release of renin by slices taken from nonhibernating ground squirrels but had no effect on those taken from hibernating squirrels. The alpha-agonist phenylephrine (10(-5) M) had no effect on slices from nonhibernating squirrels but enhanced the release rate in those from hibernating ground squirrels, providing the first evidence of in vitro stimulation of renin release by an alpha-agonist. When incubated at 11 degrees C, kidney slices from both hibernating and nonhibernating animals were unresponsive to both alpha- and beta-agonists until incubation times were doubled. Under these prolonged conditions, phenylephrine again stimulated renin release. These results indicate that both in vitro and in vivo cooling alter the responses of alpha- and beta-adrenoceptors to renin-releasing stimuli.