Uterine contractions, oxytocin affecting

An aqueous extract of hibiscus dose-dependently inhibited the rate and amplitude of uterine contractions in rats after intra-arterial injection of 1,5,10,50, or 100 mg/kg. The uterine response to hibiscus was not affected by administration of either atropine or propranolol. At the 500 mg/kg dose, hibiscus produced a slight reduction of contraction amplitude in oxytocin-precontracted uteruses (Fouda et al. 2007). 

Oxytocin, which is produced in the pituitary gland, causes the contraction of smooth muscle, including the uterus. It is used clinically to induce labor or to increase the strength of uterine contractions. Vasopressin, another pituitary hormone, regulates the secretion of water by the kidneys and affects blood pressure. The structures of vasopressin and oxytocin differ by only two amino acids. They are cyclic peptides that are hnked by a disulfide bond between two cysteine residues. 

Oxytocin 8 OXTR, GCRP, G q Affects uterine contractions... 

Two hormones produced by the pituitary gland are the nonapep-tides (peptides with nine amino acids) oxytocin and vasopressin. Oxytocin stimulates uterine contractions in labor and vasopressin is an antidiuretic hormone that regulates blood pressure by adjusting the amount of water reabsorbed by the kidneys. The structures of these nonapeptides are very similar. Only the amino acids in positions 3 and 8 are different. However, the difference of two amino acids greatly affects how the two hormones function in the body. 

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