In our present studies, we evaluated the role of the submandibular glands (SMG) on plasma inactive renin (PIR) releasing mechanisms in rats using some agents which are known to stimulate plasma active renin (PAR) release.
The results were analyzed between sialoadenectomized (SX) and sham-operated (control: C) rats. Twenty-four h after the operation, PAR releasing agents, furosemide (FRO) 2.5mg/rat/h with prior iv bolus 5mg, captopril (CAP) 5mg/rat/h with prior iv bolus 10mg, 1-Sar-8-Ile-angiotensin II (Ang II A) 300ng/kg/min, prostaglandin E1 (PGE1) 100ng/kg/min, and prostaglandin 12 (PGI2) 100ng/kg/min, were infused through femoral venous cannulae. Blood samples were taken through femoral arterial cannulae into test tubes containing 2mg EDTA-2Na. PAR was assayed by RIA, and total renin was obtained after tryptic activation. According to the responses of PIR, the agents used were categorized into three patterns: FRO increased PIR, both PGs lowered PIR, and, CAP and Ang II A had no effect on PIR release. The PIR release mechanisms by FRO were further investigated by 20mg FRO ip injection in totally nephrectomized rats. PIR increased even in nephrectomized rats, but the increase was totally canceled by the following SX. In conclusion, FRO alone among some agents studied is able to stimulate PIR release only under the existence of SMG.
