On 22/6/02 7:31 AM, "Automatic digest processor"
<[log in to unmask]> wrote:

> then it is entirely possible in my mind
> to imagine that the alveoli cells are swollen, the junctures opening up and
> allowing more immunoglobulins to be released into the milk.

This is a good thought - but with paracellular flow the milk components (and
serum derived products) travel down a concentration gradient. For instance
with the open paracellular pathway theory sodium and serum albumin will
increase in milk because the blood concentration is much higher than it is
in milk and lactose will decrease because there is negligible (or none)
lactose in blood. This is in fact a good way of measuring the opening and
closing of the paracelular pathway by measuring the secretion of lactose in
urine (being passed from milk to blood to excretion) in conjunction with
milk lactose levels.

sIgA (which is most likely synthesised in the alveoli, as it is a surface
immunoglobulin) and lactoferrin are not normally in blood  so the theory of
the open paracellular pathway would not support their passage INTO milk from
serum. An increase would mean an increase in synthesis of these proteins in
the breast - which may of course occur if there is inflammation related to
milk stasis. But also (or alternatively) with prolonged milk stasis and/or
concomitant inflammation supply will eventually drop and these proteins will
rise for these reasons.

This is why I am inclined to think that oversupply is an over synthesis
problem due to lack of feedback control. Perhaps some breasts just take
longer than others (a normal variation rather than a pathological or a
management problem) to get their local feedback mechanisms functioning
adequately - but then perhaps not.

Valerie's idea of the swollen alveolar cells allowing the pathway to open is
correct. Work done by Stelwagen in New Zealand  in cows and goats showed the
paracellular tight junctions became leaky after 18-21 hours of milk stasis
(no milking - poor old things). I expect in women this would occur much
earlier as the gland is smaller and structured differently ( with no
collecting cistern)

Regards
Cathy Fetherston
Perth Western Australia

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