速激肽受体介导的背根节辣椒素敏感的神经元膜电流的变化

全细胞电压钳记录急性分离的成年大鼠背根节（dorsalrootganglion,DRG）神经元胞体通道电流．选择对辣椒素（capsaicin）敏感的神经元,0．2nM－1μmol/L的速激肽（tachykinins,TK）,包括P物质（SP）、神经激肽A（NKA）、神经激肽B（NKB）灌流记录细胞,结果表明：TK能增大电压门控的Ca2+电流和河豚毒（TTX）不敏感的Na+电流,对电压依赖的外向K+电流呈加大和减少的双向反应;在静息膜电位水平,TK引起三种反应形式的内向电流：1）快速内向流;2）缓慢内向流;3）长时程振荡性内向流．三种速激肽受体的选择性桔抗剂能翻转TK引起的这些电流变化,用含有TK的无Ca2+或含Cd2+的外液灌流细胞,TK不再引起电压门控Ca2+电流增加。含TEA和Cs+的外液,对TK在静息膜电位水平引起的快速和缓慢内向流无明显作用;但在长时程振荡性内向流的基础上,引起一种可逆的快速内向流．含有TTX与用氯化胆硷置代NaCl的外液,或用Cd2+置代Ca2+的外液能明显减少这三种内向流,含TTX和Cd2+的外液则能几乎完全抑制它们．辣椒素敏感的DRG神经元对重复应用TK出现明显的脱敏现象．在静息膜电位水平,阿片肽能翻转速激肽引起的内向电流．DAMGO还能桔抗Sar－SP增大电压门控Ca2+电流的作用．DAMGO的拮抗作用可以被它的选择性拮抗剂β-F     

An account of significant events influencing Australian breastfeeding practice over the last 40 years

Background

Low breastfeeding duration rates reflect the pain and distress experienced by many women who discontinue breastfeeding in the early weeks and months of life. This paper explores modern key historical events that have significantly influenced Australian breastfeeding education and practice.

Method

Relevant literature reviewed from 1970 to 2010 identified key events that appear to have contributed to the decrease in Australian breastfeeding rates and the increase in women experiencing breastfeeding complications, particularly nipple pain and trauma.

Findings and discussion

The rise in institutionalisation and medical intervention in labour and birth has also medicalised midwifery practice. Technocratic intrusion and institutionalised care is contributing to the separation of the mother and newborn at birth. Delayed mother–baby initiation of breastfeeding and interruption of the duration of the first, and subsequent breastfeeds, negatively affects the innate ability of the mother and newborn to establish and sustain breastfeeding. The ‘pathologising’ of breastfeeding that involve midwives teaching women complicated and unnatural breastfeeding techniques interfere with instinctive sensory and mammalian behaviours and further contributes to the high complication rates.

Conclusion

Midwives are encouraged to reflect on their role as ‘experts’ in the breastfeeding process and give confidence to women so that they utilise their instinctive ability to breastfeed by self-determined techniques that encourage mammalian skills for newborn sustenance and survival.