ISSN:
1432-1440
Keywords:
Atrial natriuretic peptide (ANP)
;
Intracellular calcium
;
Natriuretic hormone
;
Ouabain-like factor (OLF)
;
Vascular smooth muscle cell (VSMC)
;
Platelets
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The existence of an endogenous natriuretic hormone and ouabain-like factors (OLF) has been postulated for many years. This postulate was based on our original observation that a small M.W. fraction in the serum after acute expansion of the extracellular fluid volume (ECFV) not only exhibited natriuretic activity but also inhibited the Na-K-ATPase enzyme in vitro similar to ouabain. Since then, numerous studies confirmed the presence of OLFs in serum, urine, cerebrospinal fluid, and various organs including the heart and hypothalamus. Some of these OLFs are well-known endogenous compounds, such as free unsaturated fatty acids, which inhibit in vitro transmembranous sodium transport, Na-K-ATPase and3H-ouabain binding to its membrane receptor or crossreact with digoxin antibodies. Chemically yet undefined OLFs of potentially hypothalamic origin were detected in various models of experimental and clinical hypertension and are suggested to play a pathophysiological role especially in salt- and volume-dependent forms of hypertension. Our results show that OLFs isolated from the urine of salt-loaded healthy subjects strongly enhance basal and vasopressin-stimulated release of calcium in vascular smooth muscle cells and platelets similar to the effects we had observed with endothelin. This urine fraction also exhibits natriuretic activity which increases in parallel with sodium intake. Further chromatographic separation and amino acid analysis confirmed the peptidic nature (M.W.〈1000) of the natriuretic factor(s). However, the two biological activities, namely natriuretic and ouabain-like activities, reside in distinct and chemically different compounds. In face of the previous discovery of the atrial natriuretic peptides (ANP) it is of special interest that very recent observations strongly suggest a natriuretic factor of non-cardiac origin to play an important role in the natriuresis that follows ECFV expansion. In addition, numerous experimental data point to an interaction between the ANP and OLF systems. They should stimulate once again the final identification of these yet unknown endogenous natriuretic and ouabain-like factors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01798061
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