Cardiovascular morbidity and mortality are potentiated with smoking and hypertension. The aim of this study was to investigate the effects of morphine and nicotine co-administration on cardiovascular function in two-kidney one-clip hypertensive (2K1C) rats. Thirty-two male rats were divided into four groups as follow: Vehicle, morphine, nicotine and nicotine + morphine. All drugs were administe...

Studies comparing morphine tolerance in males and females are rare, and all studies to date have utilized the rat. To generalize from findings with rats morphine tolerance was investigated in male and female mice using the tail-withdrawal test. Three and 7 days of systemic morphine injections produced significant but unequal rightward shifts in the morphine dose-response curve such that females...

Tolerance to morphine analgesia following repeated administration disturbs the continuation of opioid therapy for severe pain. Emerging evidence suggests that the development of morphine tolerance may be antagonized by painful stimuli. To clarify the detailed mechanisms of these phenomena, we examined the effects of several pain stimuli on morphine-induced tolerance. Subcutaneous (s.c.) injecti...

BACKGROUND Both the Department of Defense (DoD) and the Department of Health and Human Services (DHHS) currently require two confirmation tests to verify use of heroin, one test for total morphine and a separate test for 6-acetylmorphine (6-AM). Our aim was to determine appropriate free-codeine, free-morphine, and 6-AM cutoff concentrations that could be substituted for total-morphine, total-co...

Statins, 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors, are widely used in the management of different diseases beyond their primary indication for lowering cholesterol. Previous studies have demonstrated the neuroprotective effects of simvastatin in different animal models. In the present study, we examined the effects of simvastatin (30, 60, 100 and 300mg/kg, p.o.) on ...

Opioid agonists such as morphine have been found to exert excitatory and inhibitory receptor-mediated effects at low and high doses, respectively. Ultra-low doses of opioid antagonists (naloxone and naltrexone), which selectively inhibit the excitatory effects, have been reported to augment systemic morphine analgesia and inhibit the development of tolerance/physical dependence. This study inve...

Lubiprostone activates ClC-2 chloride channels in epithelia. It is approved for treatment of chronic idiopathic constipation in adults and constipation-predominate irritable bowel syndrome in women. We tested a hypothesis that lubiprostone can reverse the constipating action of morphine and investigated the mechanism of action. Short-circuit current (Isc) was recorded in Ussing chambers as a ma...

In earlier studies, it was shown that male rats were considerably more sensitive to the antinociceptive properties of morphine than females in several antinociceptive assays. The purpose of our studies was to examine whether these male-female differences might be due to differences in the blood and brain levels of morphine attained after its s.c. injection rather than to intrinsic differences i...

Forty patients were allocated randomly to receive one of four premedications i.m.: placebo only, morphine 10 mg plus placebo, morphine 10 mg plus cisapride 10 mg and morphine 10 mg plus cisapride 4 mg. Gastric emptying after each premedication was assessed using the oral paracetamol absorption model. The morphine only group and the morphine and cisapride 4 mg group showed delayed gastric emptyi...

A new, pharmacologically active morphine derivative, 6-succinylmorphine, was synthesized. The properties of this compound and evidence for its structure are presented. Succinylmorphine was covalently coupled to ethylamino-Sepharose. Morphine-Sepharose containing up to 40 mug of morphine did not block the electrically stimulated contraction of isolated guinea pig ileum, but after alkaline hydrol...