Key Points
- To determine the cellular localization of brain natriuretic peptide in rat atria and evaluate its cosecretion with atrial natriuretic factor into the circulation.
- Measured brain natriuretic peptide (BNP) and atrial natriuretic factor (ANF) in rat plasma, atria, and ventricles using radioimmunoassay, chromatographic analysis, and immunoblotting.
- Identified subcellular localization within atrial cardiocytes using immunohistochemistry and double-labeling immunocytochemistry.
- Evaluated plasma hormone release responses after provocative stimuli, including morphine injection and surgically induced aortocaval shunts.
- BNP colocalized with ANF within identical atrial secretory granules, presenting as two immunoreactive forms with apparent molecular weights of 14,000 and 2,500.
- Basal plasma BNP ranged from 2.6 to 4.4 fmol/ml, rising 4-fold after morphine and 7-fold after aortocaval shunt, compared to ANF increases of 50-fold and 6-fold, respectively.
- The disproportionate circulatory release of BNP relative to ANF indicates BNP may also be secreted directly from extra-atrial tissues such as the ventricles.
Structured PICO
Does morphine injection or aortocaval shunt increase BNP release into the circulation in rats?
IInterventionMorphine injection or aortocaval shunt
OOutcomeLocalization of brain natriuretic peptide (BNP) in atria and plasma levels after stimulisurrogate
This preclinical study demonstrates that BNP is colocalized with ANF in atrial granules and released into circulation in response to stimuli, suggesting a role in blood pressure and volume homeostasis.