Effects of ovariectomy on the secretory apparatus in the right atrial cardiomyocytes of middle-aged mice

OBJECTIVE : The aim of the present study was to evaluate the effects of ovariectomy on the secretory apparatus of natriuretic peptides in right atrial cardiomyocytes. METHODS: Nine-month-old mice underwent bilateral ovariectomy or sham surgery. The blood exam of the ovariectomized mice showed results consistent with castrated females. Systolic blood pressure was measured after ovariectomy (9 mo of age) and at the moment of sacrifice (12 mo of age). Fragments of the right atrium were collected and prepared for electron microscopy examination. The following variables were quantified: the quantitative density and area of the natriuretic peptide granules, the relative volume of euchromatin in the nucleus, the number of pores per 10 μm of the nuclear membrane and the relative volumes of the mitochondria and Golgi complex. RESULTS: The cardiomyocytes obtained from ovariectomized mice indicated that the quantitative density and the area of secretory granules of natriuretic peptides were significantly lower compared with the sham-operated mice. Furthermore, there was a decrease in the relative volume of euchromatin, a lower density of nuclear pores, and lower relative volumes of the mitochondria and Golgi complex in the ovariectomized mice compared with the sham-operated mice. These findings suggest a pool with a low turnover rate, i.e., low synthesis and elimination of natriuretic peptides. CONCLUSION: A lack of estrogen caused hypotrophy of the secretory apparatus in right atrial cardiomyocytes that could explain the weak synthesis of natriuretic peptides in mice. Furthermore, one of the mechanisms of blood pressure control was lost, which may explain, in part, the elevated blood pressure in ovariectomized mice. .

Effect of different salt diets on the release of atrial natriuretic peptide and its related hormonal and renal changes

The effect of different salt [NaCl] diets [deficient, low or high] on plasma atrial natriuretic peptide [ANP] level and subsequently the effect of ANP change on the other related hormonal and renal parameters were studied in male [Rattus rattus norvegicus] rats. Seventy rats were used in this study and divided into four groups: Control [15 rats], deficient salt diet [15 rats], low salt diet [20 rats] and high salt diet [20 rats]. Serum sodium, plasma ANP and cyclic guanosine 3,5-monophosphate [cGMP] levels were significantly lower; while, plasma renin activity [PRA] and serum aldosterone levels were significantly higher in rats fed on deficient or low salt diet than in the control rats. Total body weight [TBW], hematocrite [Hct], serum potassium, albumin, urea and creatinine levels remained within the normal level. On the other hand, in the group of rats fed on high salt diet, serum sodium, TBW, plasma ANP and cGMP, serum urea and creatinine were significantly increased; whereas, Hct, serum albumin, PRA and serum aldosterone levels were significantly decreased as compared with the control group with no significant change in serum potassium level

Serum atrial natriuretic peptide, lipid profile and lipid peroxidation in adriamycin therapy of leukemia and lymphoma

Serum atrial natriuretic peptide [ANP], triglycerides, cholesterol and lipid peroxides were studied in thirty-one cases of acute lymphoblastic leukemia [ALL] [including fifteen newly diagnosed cases and sixteen relapses cases], twenty-nine cases of non-Hodgkin's lymphoma [NHL] comprised fifteen newly diagnosed cases and fourteen relapsed cases, ten oncogenic controls and ten healthy controls. Adriamycin was included in therapy of studied cases and not in that of oncogenic controls. Beside full clinical examination and routine investigations to diagnose ALL and NHL cases, ECG and echocardiography were done to all cases and controls. Serum ANP, triglyceride, cholesterol and lipid peroxides were measured before adriamycin therapy, three weeks after the first remission, three weeks after the second remission and in serum of the control group. It was concluded that serum ANP in patients treated with adriamycin is helpful diagnostic tool for early detection of myocardial damage and early management even in the absence of echocardiographic changes as the rise in ANP level is related to the drug dose and not related to the malignancy itself. Serial determinations of serum triglyceride, cholesterol and lipid peroxides are helpful for early detection and prevention of myocardial damage