High-fat diet increases respiratory frequency and abdominal expiratory motor activity during hypercapnia

Abstract

Breathing disorders are commonly observed in association with obesity. Here we tested whether high-fat diet (HFD) impairs the chemoreflex ventilatory response. Male Holtzman rats (300–320 g) were fed with standard chow diet (SD) or HFD for 12 weeks. Then, tidal volume (VT), respiratory frequency (fR) and pulmonary ventilation (VE) were determined in conscious rats during basal condition, hypercapnia (7% or 10% CO2) or hypoxia (7% O2). The mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity were also evaluated in conscious rats. A group of anesthetized rats was used for the measurements of the activity of inspiratory (diaphragm) and expiratory (abdominal) muscles under the same gas conditions. Baseline fR, VT and VE were similar between SD and HFD rats. During hypercapnia, the increase of fR was exacerbated in conscious HFD rats (60 ± 3, vs. SD: 47 ± 3 Δ breaths.min−1, P < 0.05). In anesthetized rats, hypercapnia strongly increased abdominal muscle activity in HFD group (238 ± 27, vs. basal condition: 100 ± 0.3%; P < 0.05), without significant change in SD group (129 ± 2.1, vs. basal condition: 100 ± 0.8%; P = 0.34). The ventilatory responses to hypoxia were similar between groups. In conscious HFD rats, MAP and HR were elevated and the baroreflex function was impaired (P < 0.05). These data demonstrated that 12 weeks of HFD exaggerate the ventilatory response activated by hypercapnia. The mechanisms involved in these responses need more investigation in future studies.

Prospective study on intracranial pressure waveform morphology and its relationship with the development of obesity in rats

“…We found a signi cant difference in HR between OB and NOB rats, being greater in OB, different from Shiou et al 34 (2018) and Uldal et al 32 (2017). These data corroborate those of Spereta et al 36 (2018) that demonstrated to increase in HR with obese rats, with similar values to the present study. We believe that this difference may be related to increased cardiac work and respiratory rate (not assessed in this study) due to excessive weight.…”

Does the perigestational exposure to chlorpyrifos and/or high-fat diet affect respiratory parameters and diaphragmatic muscle contractility in young rats?

“…In addition, the decrease in respiratory frequency and TI with no significant effects on TE or VT failed to support the hypothesis of a major depressant effect of CPF, HFD or their combination on the control of breathing. On the other hand, respiratory failure is related to alteration of arterial blood gases (Speretta et al, 2018). Thus, the ventilator alterations observed in our study could be induced to arterial blood gases changes that need to be checked in order to confirm any respiratory distress.…”

Functional and Morphologic Dysfunctions on Airways of Rats Submitted to an Experimental Model of Obesity-exacerbated Asthma

“…Additionally, the tidal volume decreases were related in other models to lung brosis and extensive in ammation [20], which may explain some observed changes. Differently, rats fed a hypercaloric diet demonstrated an exacerbated increase in respiratory frequency and a decreased expiratory time [21].…”