Antidiuretic effect of morphine in the rat: tolerance and physical dependence.
1 Injection of rats with morphine or methadone, before they received a water load equivalent to 5% of their body weight, produced a dose-dependent antidiuretic effect. Following the antidiuresis, urine was eliminated with kinetics similar to control untreated rats. 2 The antidiuretic effect of morphine or methadone was blocked by naloxone administered before the opiate, or reversed when given after the opiate. 3 Rats implanted with morphine pellets developed a marked degree of tolerance to the antidiuretic effect of morphine. Tolerance was also obtained on injection of three daily doses of morphine or methadone over two days. 4 Withdrawal symptoms were precipitated by naloxone in rats implanted with pellets of morphine; under these conditions the animals showed a marked reduction in urine production as compared to naive rats.
D000818:Animals; D004231:Diuresis / Q000187:drug effects*; D004343:Drug Implants; D004361:Drug Tolerance; D006801:Humans; D007274:Injections, Intraperitoneal; D008691:Methadone / Q000494:pharmacology; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D012965:Sodium Chloride / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000378:metabolism
D004343:Drug Implants; D014867:Water; D009270:Naloxone; D012965:Sodium Chloride; D009020:Morphine; D008691:Methadone