Long-Term Circulatory Consequences of Perinatal Iron Deficiency in Male Wistar Rats

Abstract

Abstract-Perinatal iron deficiency (PID) has been reported to induce developmental abnormalities, including cardiovascular complications in rats. These complications are believed to be "programmed" by an aberrant perinatal environment because the changes persist long after the insult is corrected (ie, despite subsequent iron replenishment). Little is known about the mechanisms by which PID affects blood pressure in the offspring, although the kidney is likely to play a central role. The objective of this study was to investigate the circulatory complications of PID and the putative role of the kidney involved therein. Before and throughout gestation, female Wistar rats were fed either a low-iron diet (3 ppm/10 ppm Fe) or an iron-enriched diet (225 ppm Fe). After giving birth, all of the dams were placed on a standard grain-based diet. At 24 hours postpartum, hematocrits and hemoglobin levels from offspring of iron-deficient mothers were 60% and 59% of control values, respectively. Adult PID animals had greater mean arterial pressures (110 versus 106 mm Hg) and systolic blood pressures (129 versus124 mm Hg) than controls, as assessed by radiotelemetry. The relationship between renal arterial pressure and renal interstitial hydrostatic pressure, assessed in anesthetized rats, was blunted by 41% in the PID group compared with controls. In addition, arterial pressure changes were significantly greater in response to altered sodium in the PID animals compared with controls. These data confirm that PID adversely affects blood pressure control, which seems to be mediated, at least in part, by altered intrarenal hemodynamic properties.

Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats

“…Linear regression analysis was used to calculate the slopes and y intercepts of the hindlimb flow-pressure and RAP-RIHP relationships. [31][32][33] The Grubb test was conducted on all of the data sets to determine statistical outliers. All of the data are presented as meanϮSEM.…”

“…31 Therefore, in addition to characterizing the pressure-natriuresis mechanism, this moment-to-moment relationship provides a hemodynamic assessment of renal medullary vascular resistance properties, where a rightward shift along the RAP operating point is indicative of increased renal vascular resistance. [31][32][33] However, it remains unknown whether increases in renal medullary vascular resistance properties, and thereby pressure-natriuresis, occur in weaning SHRs (ie, 4 weeks old), at a time when renal organogenesis is complete. 34 We hypothesized that young SHRs are programmed to have increased vascular resistance properties and a rightward shift in the acute pressure-natriuresis mechanism before elevations in arterial pressure.…”

Nutritional Characteristics of the Dairy Cow During Early Gestation and Subsequent Growth and Cardiac Measurements of Her Offspring

“…Lacking iron during early gestation was associated with greater mean arterial pressure and systolic blood pressure in humans (Bourque et al, 2008;Gambling et al, 2003;Lewis et al, 2001;Lisle et al, 2003). Similarly, in cattle increased arterial pressure and enlargement of the aorta have been observed in offspring born to dams subjected to early gestational undernutrition (Mossa et al, 2013).…”

Moment-to-Moment Characteristics of the Relationship Between Arterial Pressure and Renal Interstitial Hydrostatic Pressure

“…The modified in vivo assessment of renal vascular properties 21,22 was based on the technique described by Roman and Cowley 16 and the direct determination of RIHP according to Ott et al 15,23 ; however, the neurohumoral control systems were left intact. The superior mesenteric artery was catheterized with heparinized saline-filled (50 IU/mL) phycoerythrin 50 tubing for continuous measurement of arterial pressure at the level of the renal artery (hereinafter referred to as RAP).…”

“…9 An electrosurgical unit (Elmed ESU30; Elmed Incorporated) was used to create a 3-mm hole into the longitudinal axis of the left kidney for insertion of a heparinized saline-filled (50 IU/mL) catheter for RIHP measurements (Tygon tubing; ID 0.64 mm; fitted with 2-to 3-mm-long polyethylene matrix with 15-to 45-m pores; Porex). 9,[21][22][23] The catheter was held in place with cyanoacrylate glue. RAP and RIHP were continuously monitored via pressure transducers (CDX3, Cobe) connected to a PowerLab/8s …”