Interaction of 4-Hydroxylated Estradiol and Potential-Sensitive Ca2 ...

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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

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