Effect of temperature on changes, induced by oestrus, in alpha- and beta-adrenoceptor activities of the rat uterus.

The alpha- and beta-adrenoceptor activities of the isolated rat uterus during the oestrous cycle were intluenced greatly by temperature changes. During dioestrus, lowering the bath temperature to 25 degrees C from 40 degrees C increased two-fold the inhibition produced by (-)-adrenaline, (-)-noradrenaline, (-)-phenylephrine and (-)-isoprenaline. During oestrus adrenaline, noradrenaline and phenylephrine produced biphasic responses of contraction followed by inhibition at 40 degrees C and isoprenaline produced only inhibition. At 25 degrees C the contractile alpha-responses either were abolished (phenylephrine) or greatly reduced (adrenaline and noradrenaline), while the inhibitory beta-effects of all four amines were increased.