Title

The Kidney as a Hub for pH Modulation: The Interrelationship of Lactate, Pulse, and Blood Pressure

ORCID

J. Mark Van Ness: 0000-0001-5902-8735

Document Type

Conference Presentation

Department

Health, Exercise, and Sport Sciences Department

Conference Title

2018 ACSM National Conference

Organization

American College of Sports Medicine (ACSM)

Location

Minneapolis, MN

Conference Dates

May 29 - June 2, 2018

Date of Presentation

5-31-2018

Journal Publication

Medicine & Science in Sports & Exercise

ISSN

1530-0315

DOI

10.1249/01.mss.0000536473.20098.78

Volume

50

Issue

5s

Publication Date

2018-05-01

First Page

421

Abstract

Following the pioneering work of Hill and Meyerhoff, in 1933, Margaria and colleagues published a compelling relationship between pH and lactate in the blood. In 1976, Sahlin and colleagues detected and presented that same relationship in skeletal muscle. These events helped make lactate metabolism one of the most famous and misunderstood phenomena in exercise physiology. We now know that rates of ATP hydrolysis and hydrogen ion clearance are fundamental to exercise-induced metabolic acidosis; however, the role of the kidney in modulation of blood lactate and pH still requires further elucidation in athletic and ill populations.

PURPOSE: To better understand the determinants of blood pH by examining the interrelationship between lactate, pH, and cardiovascular parameters in a patient population.

METHODS: We analyzed a sample of 248 patients who were admitted to a Midwestern U.S. hospital for acute trauma. All patients were assessed for predictors of pH based on complete blood count and other measurements collected during intake. Multiple linear regression tested the effect of demographic, anthropometric, and metabolic variables on blood pH.

RESULTS: Subjects were 63.3% male with a mean age of 50.5 ± 21.6 years, normal blood pH (7.3 ± 0.4), and slightly elevated lactate (2.0 ± 1.7 mmol/L). Mean arterial pressure (98.5 ± 18.5 mmHg) and heart rate (90.7 ± 18.1 bpm) were also slightly elevated. The variables that predicted significant reductions in pH were lactate (p<0.001) and pulse rate (p=0.040). The variables that predicted significant increase in pH were mean arterial blood pressure (p=0.001), temperature (p=0.010), and pregnancy status (p=0.026). Sex (p=0.316), age (p=0.714), obesity (p=0.195), and blood alcohol content (p=0.624) were not statistically significant. Injury severity score was a trending predictor (p=0.057).

CONCLUSIONS: The strong association between lactate and pH may indicate a need to re-examine components of the lactate/pH framework. The associations between blood pressure, pulse, and pH implicate the kidney; further work needs to be done in outlining renal function and its role in modulation of pH and cardiovascular function.

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