Breathing, Kidneys, and the Body That Tries to Remain in Balance

The balance of the Body-Territory is not about staying still. It is about changing continuously so that life remains possible.

In the previous blog, we saw that breathing too much can reduce CO₂.

If alveolar ventilation eliminates carbon dioxide faster than metabolism can produce it:

CO₂ ↓
→ pH tends to rise
→ respiratory alkalosis appears.

If this happens for a few minutes, the organism responds in one way.

If it persists for hours or days, another scale begins to participate.

The kidneys enter the conversation.

And here we find one of the most interesting images in this series.

The lungs can modify CO₂ rapidly.

The kidneys modify bicarbonate handling and acid excretion much more slowly.

One system moves in seconds.

The other responds to the previous movement over hours and days.

And yet both participate in the attempt to maintain one extraordinarily important variable:

pH.

pH Is Not Simply an Amount of “Acid” Floating in the Blood

pH represents, on a logarithmic scale, activity related to hydrogen ion concentration.

Small numerical changes in pH correspond to meaningful chemical changes.

In arterial blood, the organism normally keeps pH within a narrow range, approximately 7.35–7.45.

This does not happen because the blood remains chemically still.

It happens precisely because it never stops changing.

Cells produce acids.

Metabolism produces CO₂.

The lungs eliminate CO₂.

The kidneys recover bicarbonate.

They generate new bicarbonate.

They excrete nonvolatile acids.

Brazilian researcher Pedro Henrique Imenez Silva and Nilufar Mohebbi emphasize that the lungs and kidneys are the two major systems responsible for acid-base homeostasis and that this regulation is deeply connected to cellular metabolism.

Perhaps, then, we should abandon the image of balance as immobility.

Homeostasis is not the absence of movement. It is enough movement to keep certain relationships possible.

CO₂ and Bicarbonate Exist in a Relationship

We can simplify part of this physiology through the relationship:

CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻

Carbon dioxide interacts with water.

Carbonic acid is formed.

And this system relates to:

H⁺ — hydrogen ions

and

HCO₃⁻ — bicarbonate.

The Henderson-Hasselbalch equation mathematically represents a fundamental idea:

pH depends on the relationship between bicarbonate and CO₂.

Very simply:

more CO₂, with similar bicarbonate → pH tends to fall.

less CO₂, with similar bicarbonate → pH tends to rise.

That is why breathing can change acid-base balance so quickly.

The Lungs Move First

Imagine a person with:

PaCO₂ ≈ 40 mmHg.

They begin ventilating far beyond metabolic demand.

CO₂ is eliminated.

PaCO₂ falls.

Perhaps to 35.

Perhaps to 30 mmHg.

With less CO₂ available in the buffering system:

H⁺ decreases relatively
→ pH rises.

This is acute respiratory alkalosis.

At that first moment, the kidneys have not yet significantly reorganized their function.

The event happened too quickly.

Chemical buffering mechanisms respond immediately.

Renal compensation needs time.

Recent studies indicate that detectable renal responses to sustained hypocapnia may begin after approximately 3–6 hours, while broader adaptations continue over longer periods.

We can imagine:

breathing: seconds

blood chemistry: seconds to minutes

kidneys: hours to days.

These are not three separate events.

They are three temporal scales of the same Body-Territory.

When Hypocapnia Persists, the Kidneys Change What They Do

If PaCO₂ remains reduced, maintaining the same amount of bicarbonate would contribute to keeping pH excessively alkaline.

The kidneys then begin to compensate.

During sustained respiratory alkalosis, renal tubules tend to:

reduce bicarbonate reabsorption,

reduce H⁺ secretion,

and favor greater bicarbonate loss in urine.

As a result:

blood HCO₃⁻ ↓

and pH shifts back toward the physiological range.

This compensation is established physiology.

But there is a fundamental distinction:

compensation does not mean removing the original cause.

If the person continues to hyperventilate, CO₂ may remain low.

The kidneys do not “tell the lungs to stop.”

They modify another part of the relationship to reduce the disturbance in pH.

We may then find:

**low CO₂

• lower bicarbonate

• pH relatively close to normal.**

The pH value may appear less abnormal.

But the organism reached that value through a different material configuration.

The Same pH Does Not Mean the Same Body-Territory

This point connects directly with our 5D Consciousness model.

Imagine two people with a pH of 7.40.

The first has CO₂ and bicarbonate close to their usual equilibrium.

The second has reduced CO₂ and reduced bicarbonate because of compensation.

The same number:

pH = 7.40.

But not necessarily the same material state.

What changed?

molecules,

gradients,

tubular transport,

ventilation,

flows,

energy consumption,

transporter activity,

relationships among lungs, blood, and kidneys.

In 5D Consciousness, this matters.

The 3D representation of the organism’s state is not only in the final value of one variable.

It is in the distributed material configuration that made that value possible.

Two Body-Territories can show the same number while performing different physiological movements to produce it.

The Andes Show This Dialogue at a Real-World Scale

One of the clearest examples of the relationship between breathing and the kidneys occurs at high altitude.

When a person living at sea level ascends to high altitude, oxygen availability decreases.

Chemoreceptors stimulate greater ventilation.

This helps increase alveolar oxygen availability.

But it also eliminates more CO₂.

The result is:

hyperventilation
→ hypocapnia
→ respiratory alkalosis.

With continued exposure to altitude, the kidneys increase bicarbonate excretion, allowing elevated ventilation to be sustained with less disturbance of pH.

Peruvian researcher Francisco C. Villafuerte, from Universidad Peruana Cayetano Heredia, participated in a 2024 review describing these integrated adaptations in high-altitude populations and visitors.

Another recent review, with participation from Peruvian researcher Gustavo Gonzales, also describes renal bicarbonate excretion as part of acclimatization to altitude-induced hyperventilation.

The Andes show something important:

lungs and kidneys can truly build a new acid-base equilibrium together.

But altitude is not the same thing as behavioral hyperventilation.

At altitude, there is a strong hypoxic stimulus.

Therefore, we cannot simply transfer every mechanism observed there to anxiety, habitual breathing patterns, or breathwork techniques.

What If a Person Hyperventilates Chronically?

Now we reach the question that interests BrainLatam.

Some people may experience recurrent or persistent periods of ventilation above metabolic demand.

If this produces sustained hypocapnia:

physiology predicts renal compensation.

A 2024 study found, in a subgroup of women with fibromyalgia, a combination of low PaCO₂ and bicarbonate values compatible with possible renal compensation of mild chronic hyperventilation. The authors themselves interpret the finding cautiously and do not present it as a universal explanation of the condition.

This shows that the physiological state is possible.

But it does not answer our next question:

could renal compensation contribute to making a particular respiratory pattern more stable or more likely to recur?

We do not know.

This is where the Breathing-Kidney Loop begins.

Breathing-Kidney Loop: a BrainLatam Hypothesis

We can represent our hypothesis like this:

persistent excessive ventilation
→ CO₂ ↓
→ respiratory alkalosis
→ renal compensation
→ bicarbonate ↓
→ new compensated acid-base state.

Up to this point, we are close to established physiology.

The next step is hypothetical.

We ask whether this new material state could modify:

chemosensitivity,

the sensation of respiratory need,

tolerance to CO₂ changes,

learned respiratory patterns,

interoception,

and the probability of returning to the previous ventilatory pattern.

If this happened, we might have feedback:

breathing changes the kidneys
→ the kidneys change the chemical environment
→ the chemical environment changes the conditions in which the next breath occurs.

We provisionally call this possibility:

Breathing-Kidney Loop — RIM Loop

But we need to draw a clear scientific boundary:

there is currently not enough evidence to state that renal compensation “traps” a person in chronic hyperventilation.

The RIM Loop is a hypothesis.

It needs to be tested.

Where Do Post-Expiratory Breath Holds Enter?

Exhale normally.

Now imagine not beginning the next inhalation immediately.

During a post-expiratory breath hold:

no new air enters,

metabolism continues producing CO₂,

CO₂ begins to rise,

O₂ begins to fall.

The longer the hold, the greater the gas disturbance tends to become and the stronger the drive to breathe.

A 2025 review on breath-hold physiology confirms that, during voluntary apnea, CO₂ rises progressively while O₂ decreases, recruiting chemoreflexes and cardiovascular responses.

So a post-expiratory breath hold can, acutely, raise CO₂ relative to the immediately preceding level.

That is physiology.

But there is another statement we cannot make:

“30- or 40-second post-expiratory holds correct the renal compensation of chronic hyperventilation.”

We do not have enough evidence for that.

A change in CO₂ over seconds does not automatically undo a renal adaptation built over hours or days.

This difference in timescale will be essential for any future experiment.

Perhaps the Experiment Needs to Measure Two Physiological Clocks

To test the RIM Loop, ETCO₂ alone will not be enough.

ETCO₂ provides an excellent window into ventilation and short-term respiratory changes.

But the kidneys operate on another scale.

Depending on the experimental design, we would need to monitor:

ETCO₂,

pH,

blood bicarbonate or total CO₂,

electrolytes,

and possibly urinary variables related to acid-base excretion.

And we would need to follow these over time.

Not only before and after a single breath.

Because we are trying to observe two dynamics:

lungs: fast

and

kidneys: slow.

Remaining Stable Requires Never Remaining the Same

Perhaps this is the most important point in this blog.

An organism that keeps its pH near 7.40 is not frozen at 7.40.

While you read this sentence:

cells are producing CO₂,

ATP is being consumed,

protons are crossing membranes,

bicarbonate is circulating,

the kidneys are filtering plasma,

tubules are transporting ions,

the lungs are eliminating gas.

Stability emerges from movement.

In BrainLatam language:

the Body-Territory does not preserve its existence by avoiding change. It preserves certain relationships by changing continuously.

This makes the RIM Loop interesting even before we know whether the hypothesis will be confirmed.

Because it forces us to abandon one question:

“what is the normal state?”

and replace it with another:

“what movements is this organism performing in order to remain within a range that still makes life possible?”

Perhaps this is exactly what we mean by balance.

Not a fixed point.

But a dance among:

breathing
→ CO₂
→ pH
→ bicarbonate
→ kidneys
→ metabolism
→ new breathing.

And then again.

Main References

IMENEZ SILVA, P. H.; MOHEBBI, N. (2022). Kidney metabolism and acid-base control: back to the basics. Pflügers Archiv – European Journal of Physiology, 474, 919–934.
Brazilian researcher Pedro Henrique Imenez Silva presents an integrated view of renal acid-base homeostasis and shows how H⁺ transport, bicarbonate, metabolism, and energy production participate in the same regulatory system.

Chemistry versus compensation: comparing integrated respiratory-renal blood acid-base responses between acute inspired normobaric hypoxia versus sustained hypobaric hypoxia (2025). Journal of Applied Physiology.
Experimentally distinguishes the immediate chemical change produced by hypocapnia from renal compensation emerging during sustained exposure and indicates that measurable renal responses may begin after approximately 3–6 hours.

BHANDARI, M. et al. (2024). Demystifying normal-anion-gap metabolic acidosis: pathophysiology, aetiology, evaluation and diagnosis. Internal Medicine Journal.
Reviews how the kidneys reabsorb bicarbonate, generate new bicarbonate through ammoniagenesis, and excrete H⁺, providing the tubular basis for understanding renal participation in acid-base regulation.

GATTERER, H.; VILLAFUERTE, F. C.; ULRICH, S. et al. (2024). Altitude illnesses. Nature Reviews Disease Primers, 10, 43.
Includes Peruvian researcher Francisco Villafuerte and provides an Andean context for understanding how hypoxia, hyperventilation, hypocapnia, and systemic acclimatization become integrated at high altitude.

BOULARES, A.; BRAGAZZI, N. L.; GONZALES, G. F. et al. (2025). Addressing Anemia in High-Altitude Populations: Global Impact, Prevalence, Challenges, and Potential Solutions. American Journal of Hematology, 100(9), 1590–1602.
With participation from Peruvian researcher Gustavo Gonzales, describes altitude-induced hyperventilation, respiratory alkalosis, and subsequent renal bicarbonate excretion as part of physiological adaptation.

Hypocapnia in women with fibromyalgia (2024). Scandinavian Journal of Pain, 24.
Identifies a subgroup with reduced PaCO₂ and an acid-base profile compatible with possible renal compensation of mild chronic hyperventilation, showing that this physiological state can be investigated in humans without establishing universal causality.

ELIA, A.; LEMAÎTRE, F. (2025). The application of breath-holding in sports: physiological effects, challenges, and future directions. European Journal of Applied Physiology, 125, 2049–2065.
Reviews breath-hold physiology and shows that CO₂ rises while O₂ progressively falls during voluntary apnea, supporting the use of breath holds as acute perturbations rather than as proof of correction of chronic renal adaptations.

BrainLatam (2026). CO₂: The Gas That Changes the Heart, Brain, and Digestion.
Establishes the previous step in the series by connecting ventilation, CO₂, cerebral circulation, RespHRV, and NIRS, allowing this blog to extend the phenomenon into the slower timescale of renal participation.

BrainLatam (2026). 5D Consciousness / Body-Territory.
Provides the conceptual basis for understanding stability as a distributed and dynamic material configuration: molecules, energy, metabolism, flows, tensions, and movements may all change continuously even when a final variable appears stable.

The anchor sentence translates well as: “The Body-Territory does not remain in balance by staying the same; it remains possible by changing continuously.”