Chamber Respirometry Concepts

Chamber Respirometry

• Measures how animals exchange gases (oxygen and carbon dioxide)
• Animals are enclosed in a chamber
• Air continuously flows through the chamber, or gases are sealed
• Measures the concentration of gases in the air exchanged
• Pros:
  • Precise: all expired gases measured
  • Accurate
  • Controlled environment
• Cons:
  • Constrained animal behaviour
  • Risk of asphyxiation or hypercapnia
  • May be messy

Metabolism (Chamber) Treadmill

• Used to get certain animals to exercise
• Animals monitored while exercising.

Chamber Respirometry: Closed System

• Measures oxygen consumption in a chamber
• O2 level drops, measured by detecting % O2, concentration drops
• More efficient to measure all the expired gases
• Pros
  • Efficiently monitors all expired gases
  • Quality of air/water provided easier to control
• Cons
  • Risk of asphyxiation, and hypercapnia if levels get too low or high.
  • Accurate with more time scales

Mask Respirometry

• Measures respiration in animals with masks
• Measures the breathing patterns and rates of animals, and how these change between rest and exercise

Energy and Chances in Activity State

• ATP turnover (rate of the creation of ATP) and the rate that fuel (carbohydrates, fats, oxygen) are supplied to the cells aren't always instantaneous
• Example: exercising - the instantaneous spike in ATP turnover can't be seen immediately

Metabolic Efficiency

• Measures the rate of ATP production using different pathways (fast or slow)
• Aerobic metabolism rate is a slow rate of ATP production.

Rate of ATP Production

• Vary based of the pathway
• Phosphocreatine (fast)
• Glycolysis (fast)
• Aerobic metabolism (slow)

Dependence on Oxygen

• Aerobic metabolism: needs oxygen
• Phosphocreatine and Glycolysis do not require oxygen.

Fuel Diversity

• Phosphocreatine and Carbohydrates used as fuel
• Lipids and Amino acids as stored fuel

O2 Consumption and Metabolic Rate

• O2 consumption/CO2 production measured at a respiratory interface for measuring rates of metabolism
• Does not necessarily reflect real-time O2/CO2 production in tissue

Integrating Power and Metabolic Fuel Source

• Inverse relationship between the maximum power (rate of energy production) and the sustainabilit of that energy (ie: the size of the available energy store)

O2 Consumption and Metabolic Rate

• O2 consumption can remain high after returning to a lower activity level. This is because glycogen stores are being replenished and the breakdown products (lactate and creatine) are being metabolized with aerobic metabolism.
• Cori Cycle- use lactate to produce glucose
• Lactate Shuttle conversion pyruvate to acetyl CoA
• Creatine- helps create ATP (rebuilding of phosphocreatine)

Metabolic Rate: Some Definitions

• Basal Metabolic Rate (BMR): Metabolic rate of a homeothermic animal at rest in a thermal neutral zone, typically after not consuming food recently.
• Standard Metabolic Rate (SMR): Similar to BMR but in a poikilothermic animal.
• Resting Metabolic Rate (RMR): Metabolic rate of an animal under defined resting conditions, not necessarily a defined inactive phase

Maximum Aerobic Metabolic Rate (VO2max)

• Maximum sustained oxygen uptake (VO2).

Supramaximal Metabolic Rate

• Burst of physical activity
• The actualized metabolic rate naturally

Field Metabolic Rate

• The actual realized metabolic rate of an animal acting in its natural environment

This quiz covers the principles of chamber respirometry, including how animals exchange gases within enclosed environments. It evaluates understanding of both closed and open systems and the advantages and disadvantages of using such methods for measuring metabolic rates in animals.