PMID- 19176886 OWN - NLM STAT- MEDLINE DCOM- 20090605 LR - 20200930 IS - 0363-6119 (Print) IS - 0363-6119 (Linking) VI - 296 IP - 4 DP - 2009 Apr TI - Responses of the trout cardiac natriuretic peptide system to manipulation of salt and water balance. PG - R1170-9 LID - 10.1152/ajpregu.90880.2008 [doi] AB - Natriuretic peptides (NPs) are evolutionarily conserved hormones that affect blood pressure and fluid volume through membrane-bound guanylate cyclase (GC)-linked natriuretic peptide receptors-A and -B (NPR-A and NPR-B, respectively) in a variety of vascular, renal, and other tissues. The principal physiological stimulus for cardiac NPs in fish is somewhat debated between two prominent theories: regulation of salt balance (osmoregulatory hypothesis) or prevention of volume expansion (cardioprotective hypothesis). In the present study, we examined atrial and ventricular expression of trout NPs, atrial (ANP), brain (BNP), and ventricular (VNP) using Northern (mRNA), Western (NP pro-hormone), and qPCR (GC-NPR-A and -B mRNA) blot analysis following independent manipulation of plasma salt and volume levels after chronic exposure to freshwater (FW; volume loaded, salt depleted), saltwater (SW; volume depleted, salt loaded), or freshwater trout fed a high-salt diet (FW-HSD; volume and salt loaded). We also measured NP transcriptional response to acute (2 h) volume expansion with dialyzed plasma (VE; 80% blood vol) or volume depletion by hemorrhage (VD, 20% blood volume every 30 min for 2 h) with real-time PCR. In essentially all instances, increased expression of the NP system was associated with FW-HSD or plasma expansion. There were no differences in NP expression between chronically adapted FW and SW fish, and hemorrhage decreased atrial ANP and VNP mRNA. These results indicate that rainbow trout cardiac NPs and cardiovascular GC-NPRs respond principally to volume, not salt overload, and this suggests that the primary function of trout cardiac NP system is to protect the heart. FAU - Johnson, Keven R AU - Johnson KR AD - Indiana School of Medicine, South Bend, IN 46556, USA. FAU - Olson, Kenneth R AU - Olson KR LA - eng PT - Journal Article PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20090128 PL - United States TA - Am J Physiol Regul Integr Comp Physiol JT - American journal of physiology. Regulatory, integrative and comparative physiology JID - 100901230 RN - 0 (Chlorides) RN - 0 (Fish Proteins) RN - 0 (Natriuretic Peptides) RN - 0 (Protein Precursors) RN - 0 (RNA, Messenger) RN - 0 (Sodium Chloride, Dietary) RN - 114471-18-0 (Natriuretic Peptide, Brain) RN - 85637-73-6 (Atrial Natriuretic Factor) RN - 9NEZ333N27 (Sodium) RN - EC 4.6.1.2 (Receptors, Atrial Natriuretic Factor) RN - EC 4.6.1.2 (atrial natriuretic factor receptor A) RN - EC 4.6.1.2 (atrial natriuretic factor receptor B) SB - IM MH - Adaptation, Physiological MH - Animals MH - Atrial Natriuretic Factor/metabolism MH - Blood Volume MH - Chlorides/blood MH - Fish Proteins/genetics/*metabolism MH - Fresh Water MH - Myocardium/*metabolism MH - Natriuretic Peptide, Brain/metabolism MH - Natriuretic Peptides/genetics/*metabolism MH - Oncorhynchus mykiss/blood/*metabolism MH - Protein Precursors/metabolism MH - RNA, Messenger/metabolism MH - Receptors, Atrial Natriuretic Factor/genetics/*metabolism MH - Seawater MH - Sodium/blood MH - Sodium Chloride, Dietary/metabolism MH - Time Factors MH - *Water-Electrolyte Balance EDAT- 2009/01/30 09:00 MHDA- 2009/06/06 09:00 CRDT- 2009/01/30 09:00 PHST- 2009/01/30 09:00 [entrez] PHST- 2009/01/30 09:00 [pubmed] PHST- 2009/06/06 09:00 [medline] AID - 90880.2008 [pii] AID - 10.1152/ajpregu.90880.2008 [doi] PST - ppublish SO - Am J Physiol Regul Integr Comp Physiol. 2009 Apr;296(4):R1170-9. doi: 10.1152/ajpregu.90880.2008. Epub 2009 Jan 28.