A Low Protein Diet Causes an Increase in the Basal Levels and Variability of Mean Arterial Pressure and Heart Rate in Fisher Rats

Abstract

The correlation between nutrition and cardiovascular related disorders is a well-established fact. Previous work from our Laboratory has suggested a significant compromise of cardiovascular reflexes in conscious rats submitted to a low-protein (LP) diet. Our working hypothesis is that the basal level of mean arterial pressure (MAP), variability of the mean arterial pressure (VMAP), heart rate (HR) and variability of heart rate (VHR) are altered in rats submitted to a protein restricted diet. Two experimental groups were used: control group (normal protein 15%, NP) and malnourished group (low-protein 6%, LP). In order to verify the efficiency of the dietary restriction we measured body weight, total blood protein, plasma albumin, urea and glucose. Our experiments demonstrated that the malnourished rats presented augment levels of basal MAP (LP 122+/-2 mmHg vs. NP 113+/-1 mmHg) and of VMAP (LP 12.8+/-1.5mmHg vs. NP 9+/-1mmHg) when compared to the control group. We observed similar increased levels, in the malnourished group, for both HR (LP 429+/-8 bpm vs. NP 381+/-7bpm) and VHR (LP 67.6+/-8.3bpm vs. NP 44.4+/-4.9bpm). Our results suggest a correlation between the LP diet in Fisher rats and the increased basal levels of mean arterial pressure, HR and their respective variability.

Malnutrition affects the pressor response to microinjection of L-glutamate into the RVLM of awake rats

“…Also, there may be diff erences related to these two experimental models. Studies suggest that malnutrition during discrete periods of life (e.g., gestation, lactation, during weaning and after weaning) can produce diff erent levels of homeostasis imbalance; nevertheless, there is a consensus that protein deprivation in any period of life can lead to cardiovascular and metabolic imbalances (Barker, 2007;Cohen, 2004;El et al, 1999;Gallo, 1981;Oliveira et al, 2004;Roseboom et al, 1999). Unfortunately, there are few studies addressing post-weaning protein malnutrition and most of them are from our group.…”

“…Previous studies from our lab have shown that afterweaning malnutrition affects neural mechanisms involved in cardiovascular homeostasis (Bezerra et al, 2011a;Bezerra et al, 2011b;Loss et al, 2007;Martins et al, 2011;Oliveira et al, 2004;Penitente et al, 2007;Tropia et al, 2001). While the exact mechanism remains to be understood, there is evidence indicating that malnutrition can aff ect the release of neurotransmitters and receptor affi nity in several areas of the central nervous system (El et al, 1999;Gotoh et al, 1996;Seidler et al, 1990) The rostral ventrolateral medulla (RVLM) is a bulbar site among the neural pathways of cardiovascular refl exes (e.g., barorefl ex); it contains reticulo-spinal neurons that innervate the pre-ganglionic sympathetic neurons (Ross et al, 1984).…”

Experimental immunology The effect of vitamin B 6 supplementation of protein deficiency diet on hematological parameters in the blood of rats subjected/non subjected to physical exertion – a pilot study

“…It also affects cardiovascular and immunology system due to endothelial dysfunction, hypertension and anemia syndrome or disturb growth and development of thymus and spleen [3,17,25]. Protect role against protein deficiency in cardiovascular and immune system can play vitamin B 6 .…”

Effects of nutritional parameters on nocturnal blood pressure in patients undergoing hemodialysis

“…In one study, Fisher's rats fed a low protein diet had an elevated mean arterial pressure, mean arterial pressure variability, heart rate, and heart rate variability compared to control rats on a normal diet. 24 Tozawa et al reported that blood pressure variability was a poor prognostic risk factor for cardiovascular disease in patients with end-stage renal failure. 25 Twenty-four-hour blood pressure variability is an independent risk factor for cardiovascular mortality 26 and is associated with end organ damage.…”