Atrial natriuretic peptide and its mRNA in heart and brain of vasopressin‐deficient Brattleboro rats

Abstract

To understand the secretion and synthesis of atrial natriuretic peptide we measured immunoreactive atrial natriuretic peptide from plasma, heart tissues and brain areas, and ANP mRNA was determined from heart auricles and ventricles of vasopressin-deficient Brattleboro rats (DI) and from desmopressin treated Brattleboro rats (DI+DDAVP). Long-Evans rats (LE) served as controls. DI+DDAVP rats were given for 3 days sc. injections of 0.5 micrograms 1-desamino-8-D-arginine vasopressin in 1 mL saline twice a day. The rats were housed in single metabolic cages and urinary output and water intake were measured daily. All the body and organ weight parameters were similar in the three groups when the rats were killed. No change was seen in the plasma ANP level between the groups. The right ventricle of DI+DDAVP rats had significantly (P < 0.05) higher concentration of ANP than LE rats (15.8 +/- 4.4 vs. 3.4 +/- 0.6 ng mg-1 tissue). The left ventricle of DI and DI+DDAVP had significantly (P < 0.05) lower amounts of ANP mRNA than LE rats (0.5 +/- 0.2 vs. 1.3 +/- 0.2 and 0.5 +/- 0.1 vs. 1.3 +/- 0.2 arbitrary units). In the hypothalamus, the ANP concentration was significantly (P < 0.05) lower both in DI and in DI+DDAVP rats than in LE rats (9.3 +/- 1.3 vs. 14.5 +/- 1.6 and 6.1 +/- 0.6 vs. 14.5 +/- 1.6 pg mg-1 tissue). To conclude, although the water intake and urinary output of DI rats were changed towards normal with desmopressin treatment, the heart ventricular and hypothalamic ANP did not parallel the change.(ABSTRACT TRUNCATED AT 250 WORDS)

Streptozotocin-induced diabetes has differential effects on atrial natriuretic peptide synthesis in the rat atrium and ventricle: a study by solution-hybridization-RNase protection assay

“…A similar differential RNA synthesis between the atrium and the ventricle has been noted (this time a decrease in the ventricle) in the vasopressin deficient Brattleboro rats [20]. Stretch is believed to be a common haemodynamic stimulus for synthesis and release of ANP within the heart [3].…”

Brain natriuretic peptide (BNP) gene expression in the heart of vasopressin‐deficient Brattleboro rats

“…A 3-day DDAVP treatment of DI rats shifted the fluid balance of these animals towards normal as measured as water intake, urinary output and serum and urinary osmolality (see Arjamaa et al 1995). The ventricular weight : body weight ratios which indicated a possible ventricular hypertrophy and changes in haemodynamics were the same (P 0n05) in all groups (Arjamaa et al 1995). In the present study, the amount of BNP mRNA in the right auricle, normalized to the GAPDH mRNA content, was constant in LE, DI and DIjDDAVP rats.…”

“…The animals in these experiments and the experimental design were the same as used in the study of Arjamaa et al (1995). Briefly, male Long-Evans (LE) and agematched homozygous Brattleboro rats (DI) were obtained from Charing Cross and Westminster Medical School (Dr Lansdown, University of London).…”

“…The rats were housed in metabolic cages under controlled conditions and the water and ion balance of the animals was validated. Serum osmolality, fluid consumption, urinary output and osmolality were measured (Arjamaa et al 1995). A group of DI rats received 0n5 µg 1-desamino-8--arginine vasopressin (DDAVP) twice a day as subcutaneous injections for 3 days (DIjDDAVP).…”

“…Brattleboro rats are deficient of vasopressin and they excrete large amounts of dilute urine and have elevated serum osmolality and sodium (Valtin 1976). We showed previously that in Brattleboro rats, which were given peripherally DDAVP (desmopressin) which moved the water intake and urinary output towards normal, the heart ventricular and hypothalamic atrial natriuretic peptide (ANP) did not parallel the change (Arjamaa et al 1995). Therefore, we hypothesized that this chronic change in fluid balance brought about in Brattleboro rats could be associated with changes in the BNP mRNA levels of the heart.…”