1955_Evarts_121_2.pdf

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SOCIETY
PROCEEDINGS
moval of ionic calcium. ATP forms a complex ion with
calcium with a dissociation
constant
considerably
lower than that of citrate (K for CaATP complex-
8.7 X ro-
5
M/l.; Cacitrate complex 6.I X ro-
4
M/l.).
Experiments
were performed with these substances
and with altered calcium concentration
of Ringer's
solution on isolated curarized sartorii of
Rana piplens,
Threshold
concentrations
for spontaneous
activity
were 1.3 mxr for ATP and 2.6
mx
for citrate in normal
Ringer's solution. From the dissociation constants the
ionic calcium was calculated to be 0.3 mxr, which is
also the threshold
concentration
for spontaneous
activity when the calcium content of Ringer's is
reduced and the test substances omitted. Increasing
Ringer calcium raised the required threshold concen-
tration of ATP in the manner expected from the mass
action relationship. It is concluded that the effect of
ATP is primarily on Ringer's solution and only m-
directly on the muscle cell.
Effects oj abdominal
safety
belts.
ALFRED F. FASOLA,
*
ROLLO C. BAKER* AKDFRED A. HITCHCOCK.Lab. of
Aviation Physiology, Ohio State Univ., Columbus.
Histological examination of the heart, lungs, liver
and kidneys of animals subjected to sudden and rapid
compression of the abdomen showed the heart and
kidneys to be extremely vulnerable to such forces.
Though damage to the liver and lung was also noted,
these changes were not considered as significant with
respect to the maintenance
of functional activity.
Fragmentation
of myocardium,
extrusion of nuclei,
disseminated hemorrhages
and separation of muscle
fibers were common findings in all animals. Kidney
damage
was indicated
by rupture
and extreme
con-
of
gestion of the interlobular
vein with extravasation
instead of one volley. Long-latency unit responses have
not been described previously in the thalamus. Their
occurrence in the geniculate in the absence of cortex
indicates that they cannot be due to thalamocortical
reverberation.
They may represent
I)
long-continued
unit firing to a single stimulus, 2) long-continued
circulation of impulses within the lateral geniculate or
3) reverberation
of impulses through
undescribed
pathways outside the lateral geniculate.
Effects oj physiological subnormality and LSD on post-
tetanic potentiation
oj lateral
geniculate
potentials.
EDWARD V. EVARTS A~'D JOHN R. HUGHES (intro-
duced by WADE H. MARSHALL). Natl, Inst. of
Mental Health, Natl. Insts. of Health, Bethesda, Md.
In a previous communication,
Evarts and Marshall
iProc. Am. Neurol. A.,
r955) demonstrated
a sim-
ilarity between the excitability
cycles of geniculate
soma responses to paired optic-nerve shocks during
physiological subnormality
and subnormality
induced
by lysergic acid diethylamide
(LSD). In the present
study, the degree of post-tetanic potentiation (PTP) of
geniculate soma responses is compared under these
two forms of subnormality.
The geniculate soma re-
sponse to single shock to the contralateral optic nerve
was recorded in nembutalized or decerebrate cats. In
nembutalized animals, LSD (0.r6 mg/kg i.v.) produced
a marked decrease (up to 90%) in the amplitude of the
soma response; a 20-sec. tetanus of maximal shocks at
soo/sec. applied to the optic nerve during LSD-
induced depression was followed by an increase in soma
amplitude up to 700%. Similar potentiation was seen
in decerebrate preparations,
though the quantity of
LSD required to produce equivalent decrease in soma
amplitude was 2-3 times greater. In other experiments,
physiological subnormality
was induced by preceding
each single test shock by a volley of 12 shocks (.+00/
sec.). Under these conditions, PTP was seen for a
period of several minutes following a co-sec. tetanus of
maximum shocks at soo/sec. It is concluded that both
physiological subnormality
and subnormality induced
by LSD lead to an enlargement
of the subliminal
fringe, and that such an enlargement
is associated
with a high degree of PTP.
blood into the collecting tubules. Hemorrhages
All livers showed congestion
sinusoicls. Hemorrhagic
the continuity
the extent
of the central
radiated
veins and
of
and
than
from the pelvic region of the kidney toward the cortex.
invasion
caused disruption
capacity,
of the hepatic cells. Because of the size
lesions of
of this viscus, its excellent regenerative
this organ were considered
lesions of either heart
were noted in only
diaphragmatic
a probable
transverse
the
ity
I
to which damage was prevalent,
to be less significant
or kidney. Lesions of the lungs
case at the interior border of the
of deceleration
provide
Nons
pecificity
oj A'TPscontraction oj
iivingmuscie.
GERTRUDEFALK (introduced by J. W. WOODBURY).
Dept.
of Pharmacology,
Univ. of Washington
School of Medicine, Seattle.
Previous work (FALK and GERARD,I954) has demon-
strated that adenosine triphosphate-induced
contrac-
tion of intact, isolated, striated muscle depends on
membrane
activation;
ATP injected intracellularly
is ineffective in altering mechanical state. The mecha-
nism by which ATP produces spontaneous propagated
action potentials has been investigated. It can be shown
that the effect is non-specific and depends on the re-
lobe. High speed E-rays (50 frames/sec.)
of the mechanism
for the oc-
of maximum
of
above
taken of the heart at the instant
explanation
diameter
currence of cardiac damage. Measurements
myocardium
of this
tissue
of
approximately
to
show sudden and rapid stretch
25-30%
control. This rapid stretch beyond the limits of elastic-
is considered
be of sufficient
vessels and
intensity
to cause rupture
of the coronary
framentation
of the myocardium.

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