Page 22 - Veterinary Laser Therapy in Small Animal Practice

8 Veterinary Laser Therapy in Small Animal Practice

absorption process to occur. We can see the results, hydrogen ions (protons) outside the mitochondria than
though, and all of what I’ve mentioned here is very there are on the inside, this complex likes to produce
demonstrable. ATP. Within this chain there are several processes
Pressure waves in light-exposed water are very real that move electrons along and pump protons up and

and they change many properties of water including out of the mitochondria. The last and most powerful
viscosity, pH, translucency, and permeability. Volumes of these pumps happens inside the cytochrome oxidase
have been written on the subject. [9–12] Supra-natural complex. It involves an oxygen molecule (O ) combin-
2
oxygenation of blood has been shown to be induced ing with four electrons and eight internal protons to
by light incident on hemoglobin. [13–15] We’ll get into create two water molecules (H O) and pumping four
2
more of that when we talk about light in the blood. But protons out.
I want to spend some time on what happens in the cells So next time your kid (or grandkid) asks you why you

so we can better understand what the rest of this book need oxygen, you tell them it is the final electron accep-
is about. tor in the electron transport system. Mr. Solomon, my
ninth grade biology teacher, told me I’d use that once
1.5 Light’s targets within the cell more in my life. Shout out!
In the mitochondria, where ATP (the cell’s energy cur- 1.5.1 Cytochrome C
rency) is produced, and where a lot of the incident light
is absorbed, some very productive things can be done This is the last “push” needed to turn the ATP synthase

with light. engine and produce a molecule of ATP. The mobile
First, some quick-and-dirty on how cells metabolize. carrier that delivers the electrons to cytochrome oxi-
Insert a full volume of textbooks on cellular biology. dase is called cytochrome c, and so when they meet and
When you’ve spent years reading all of those, one of the cytochrome c delivers its electrons, it is called (again,

only things you’ll remember is a fundamental process quite fittingly) cytochrome c oxidase. But it only deliv-
called the electron transport chain (Fig. 1.2), which ers electrons one at a time, and the oxygen molecule
ends up with the production of ATP. On the mem- needs four of them for cytochrome oxidase to do its
brane of a cell’s mitochondria lives a complex that syn- thing. So it has to go back and forth four times for each
thesizes ATP, quite conveniently called ATP synthase. ATP molecule.

The fuel for this complex is a cross-membrane proton Enter, the light. Here is one of the most significant

potential. All this means is that when there are more findings of laser research – ever – first discovered by
Tiina Karu: “[laser irradiation] causes either a (tran-
sient) relative reduction of … cytochrome c oxidase,
Mitochondrial intermembrane space or its (transient) relative oxidation, depending on the
initial redox status.” [16] In English? This means that

H + H + H + H + if cytochrome c is in possession of an electron it is
Ubiquinone Cytochrome C more likely to oxidate, i.e. give up its electron (thereby
increasing its oxidation state) to cytochrome oxidase.
And as if that wasn’t cool enough, the converse is
also true, that if cytochrome c is not in possession of
an electron, it is more likely to reduce, i.e. accept an
NADH NAD + 2H + 1/2 O H O electron (thereby reducing its oxidation state) from its
2 2 H +
ADP + P ATP predecessor complex when it absorbs light.
1 1

NADH Cytochrome Cytochrome ATP This is the double whammy. Cytochrome needs to
reductase reductase oxydase synthase do both things in its natural process, called a “redox”
Figure 1.2 The electron transport chain. Once oxygen gets to cycle (see how they did that with the name: reduction
the cell and migrates to the mitochondria, these membrane- plus oxidation equals redox). And light helps both, in
based complexes act on it until ATP is produced by ATP whichever way the cell needs it to at that moment to

synthase. produce more ATP. This can happen on very very short
Illustrator: Elaine Leggett. timescales, and so the more light incident on a cell in

REDONDO PRINT (4-COL BLEED).indd 8 08/08/2019 09:46