Lactation and pregnancy effects on blood flow to mammary and reproductive systems in heat-stressed rabbits.
This study used radioactive microspheres to examine blood flow distribution in the mammary and reproductive systems of hyperthermic (+1 degrees C), anesthetized laboratory rabbits at different stages of pregnancy and lactation. Ovarian, cervical and oviductal blood flows decreased by 20-30% during heat stress while vulval blood flow rose by 40%, irrespective of pregnancy and/or lactation status. Mammary blood flow was unaltered during heat stress at most pregnancy and/or lactation stages, with the exception of a 35% decrease in non-pregnant rabbits in early lactation. Uterine blood flow in non-pregnant rabbits in early and peak lactation decreased by 42% and rose by 33%, respectively. Uterine blood flow response to heat stress in pregnant animals varied among tissues: no changes occurred in the flow to implantation sites (early pregnancy) or to inter-embryonic segments (mid- to late pregnancy); that to gestation sacs decreased by 12-40% at the different lactation stages; and that to maternal placentas decreased in the lactating state by 18%, and rose in the non-lactating state by 50%. Results indicate that pregnancy and lactation modulate vasomotor responses to heat stress in mammary and reproductive tissues, and that the extent of the modulation depends upon their respective stages.
Lublin
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A
Department of Animal Science, Faculty of Agriculture, Hebrew University, Rehovot, Israel.
Wolfenson
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D
D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D005836:Genitalia, Female / Q000098:blood supply*; D006358:Hot Temperature; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000098:blood supply*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011817:Rabbits / Q000502:physiology*; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology; D014599:Uterus / Q000098:blood supply; D014666:Vasomotor System / Q000502:physiology