Authors
Abstract
Background and Purpose: New Pressor Protein (NPP) is a human plasma enzyme structurally related to b-FXIIa, which potently raises Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP) and Heart Rate (HR) in bioassay rats. These effects are strongly potentiated in nephrectomized (2NX) rats. Concurrently, there is a massive release of catecholamines from adrenal glands. This study is carried out to investigate NPP's mechanism of action and whether ganglionic blockade can affect NPP's responses by Pentolinium in 2NX rats.
Method and Materials: Male Wistar rats, weighing 300-350g, were selected. In the nephrectomized group, after 24 h 2NX, animals were anesthetized by Inactin and ganglionic blocking agent Pentolinium (19.2 mg/kg s.c.) (P+ group) was injected. Measurements of SBP, DBP and HR were done in response to intravenous injection of NPP (5, 20 uL plasma equivalent) or purified b-FXIIa (300 ng/kg). The results of this group (P+) were compared with those of the (P-) group.
Results: These results show that NPP and purified b-FXIIa can increase SBP, DBP and HR in both groups (sham-2NX or 2NX rats). These responses in (P+) nephrectomized rats are significantly higher than (P-) nephrectomized rats (P?0.01 for each response). However, in (P+) nephrectomized rats, the increment in SBP and DBP responses are more than HR response.
Conclusion: It is concluded that NPP and b-FXIIa can produce such cardiovascular responses in rats. Although NPP does not require ganglion blockade for these responses, in P+ rats these responses have been potentiated and this potentiation is significant in nephrectomized rats. The results confirm the structural and functional relations between NPP and bFXIIa. It also indicates that there is interaction between cholinergic and peptidergic pathways for producing cardiovascular effects of NPP.
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