amrinone. (ROC blocker,. Sterling. Winthrop,. Rensselaer,. NY) specifically inhibited the constrictor response to pheny!ephrine, whereas. D-600. (PSC blocker,.
BIOLOGY
OF
36, 369-375
REPRODUCTION
(1987)
Interaction of 4-Hydroxylated Estradiol and PotentialSensitive Ca2 Channels in Altering Uterine Blood Flow during the Estrous Cycle and Early Pregnancy in Gilts1 S. L. STICE,3
S. P. FORD,2’3
J. P. ROSAZZA,5
and
Department Iowa
and
ORDEN4
of Animal Science3 State University
Ames, Departments
D. E. VAN
Iowa
50011
and of Obstetrics
and
Gynecology4
Medicinal
Chemistry5
University Iowa City,
of Iowa Iowa 55240
ABSTRACT This
study
stimulated
was
conducted
uterine
to
hyperemia.
define
further
Previous
studies
blood flow (UBF) result from alterations to a1 -adrenergic agonists). Tone changes result in short-term reductions in luminal alterations respectively.
in Ca2+ Uterine
uptake and
included
increased
tone
after
exposure
uptake arteries
of ‘ from
Ca before and after Day 13 nonpregnant
greater
significantly
arteries
from
P and
estrous
arterial
13
gilts,
segments
to
than
NP gilts which
from
KC1,
were
Day
2)
the
similar
13 NPgilts
vessels
flow
the
(UBF)
estrous is highly
to-progesterone a!., highest
1982; flow
cycle
ratio Ford
and
at estrus
of the
correlated in
pig, with
systemic
other.
the
lowest
1979), during
similar
et
with
the lutea!
Department Ames, IA
of 50011.
Animal
in estrogen-
changes
in uterine (reactivity changes result from
channels 0),
a1 -agonist
The
and
determined
of
(ROCs), on Day 13 of
9 gilts
phenylep
BPP
and
responses
responses
of arteries
reduced for
brine,
45Ca
vessels
from
uptake Day
3) of and
of uterine from
Day by
13
uterine
13 P or estrous
ovarian (estrus) or conceptus to catechol estrogens, which
the cycle. UBF (Dickson
and
Contractility were similar
(Day block
Administration et a!., 1969;
13 P) PSCs
of estrogen Van Orden et
progesterone antagonizes estrogen’s (Caton et a!., 1974; Resnik et a!.,
1977). during
During pregnancy, the estrous cycle
until
UBF is similar to that Days 12 and 13 when a
3-
4-fold
in
flow
to
Christenson, the porcine
increase
1979) coincidentally conceptus to produce
occurs with the estrogens
(Ford ability (Perry
and of et
a!., 1976) and catechol estrogens (Mondschein et a!., 1985). During the estrous cycle, uterine arterial tone (resistance to stretch) is lowest at estrus when ovarian estrogen production is high, whereas during pregnancy,
Grant
Dr. S. P. Ford, State University,
gilts. BPP
a!.,1983), whereas vasodilatory effects
Accepted September 4, 1986. Received May 5, 1986. ‘Journal Paper No. J-1 1945 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa; Projects 1994, 2443 and 2444; and supported in part by United States Public Health Service HD06380. 2Reprint requests: 11 Kildee Hall, Iowa
the
40H-E2
either of estrogens
phase increases
estrogen-
the
addition,
to those
accompanying metabolism
(Henricks the
to
estrous
than
In
blood
the
blood
Christenson, and
uterine
from
(p< 0.05)
each
UBF the
in response
INTRODUCTION
During
that
to the CE 4-hydroxylated estradiol (40H-E2). and Day 13 pregnant (P) gilts to phenylephrine of
to levels
gilts. These data suggest that increased production of estrogens may result from on the vascular smooth muscle membrane.
as intermediates
suggest
channels (PSCs) and receptor-operated removed from 6 gilts at estrus (Day
greater to
(CE)
strongly
tone (distensibility) and/or contractility baseline rate of flow, whereas contractility in uterine arterial tone and contractility
contractility
exposure (NP) were
estrogens
laboratory
on Day 13 of the estrous cycle (low estrogen, low UBF). Arterial perfusion pressure [BPP] to a constant intraluminal flow) and
contractility
to KCI
of catechol our
in uterine arterial appear to set the diameter. Changes
high UBF), and 8gilts 1) initial tone (baseline
(p
