Biomaterial Database

Effects of relaxin on blood pressure and the release of vasopressin and oxytocin in anesthetized rats during pregnancy and lactation. 1994

L J Parry, and R S Poterski, and A J Summerlee

Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.

The effects of porcine relaxin (pRXN) on arterial blood pressure and on the release of vasopressin (VP) and oxytocin (OT) were investigated in urethane-anesthetized rats at different stages of pregnancy and lactation. Acute i.v. pRXN (5 micrograms) caused a significant increase in systolic and diastolic blood pressure in pregnant and lactating rats. However, the pressor response was attenuated from Day 14 of pregnancy to Day 1 of lactation. The hormone had no effect on blood pressure in Day 16, Day 19, or Day 21 pregnant rats. At all stages of pregnancy and lactation, i.v. pRXN caused a significant increase in plasma VP concentrations. This response was attenuated in Day 19 and Day 21 pregnant and in Day 1 lactating rats. Intravenous pRXN also caused a significant, short-term increase in plasma OT in pregnant and lactating rats. The OT response to pRXN was attenuated on Day 16 of pregnancy, and pRXN had no effect on plasma OT in late-pregnant rats. The data in this study demonstrate that pRXN causes an increase in both arterial blood pressure and VP and OT release in anesthetized pregnant and lactating rats. However, these effects are either reduced or not observed in late-pregnant and early-lactating rats.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007774	Lactation	The processes of milk secretion by the maternal MAMMARY GLANDS after PARTURITION. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including ESTRADIOL; PROGESTERONE; PROLACTIN; and OXYTOCIN.	Lactation, Prolonged,Milk Secretion,Lactations, Prolonged,Milk Secretions,Prolonged Lactation,Prolonged Lactations
D010121	Oxytocin	A nonapeptide hormone released from the neurohypophysis (PITUITARY GLAND, POSTERIOR). It differs from VASOPRESSIN by two amino acids at residues 3 and 8. Oxytocin acts on SMOOTH MUSCLE CELLS, such as causing UTERINE CONTRACTIONS and MILK EJECTION.	Ocytocin,Pitocin,Syntocinon
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011270	Pregnancy, Animal	The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH.	Animal Pregnancies,Animal Pregnancy,Pregnancies, Animal
D012065	Relaxin	A water-soluble polypeptide (molecular weight approximately 8,000) extractable from the corpus luteum of pregnancy. It produces relaxation of the pubic symphysis and dilation of the uterine cervix in certain animal species. Its role in the human pregnant female is uncertain. (Dorland, 28th ed)	Relaxin B
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D005260	Female		Females
D000758	Anesthesia	A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures.
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia