Intravenous colforsin daropate, a water-soluble forskolin derivative, prevents thiamylal-fentanyl-induced bronchoconstriction in humans

The Natural cAMP Elevating Compound Forskolin in Cancer Therapy: Is It Time?

Cancer is a major public health problem and the second leading cause of mortality around the world. Although continuous advances in the science of oncology and cancer research are now leading to improved outcomes for many cancer patients, novel cancer treatment options are strongly demanded. Naturally occurring compounds from a variety of vegetables, fruits, and medicinal plants have been shown to exhibit various anticancer properties in a number of in vitro and in vivo studies and represent an attractive research area for the development of new therapeutic strategies to fight cancer. Forskolin is a diterpene produced by the roots of the Indian plant Coleus forskohlii. The natural compound forskolin has been used for centuries in traditional medicine and its safety has also been documented in conventional modern medicine. Forskolin directly activates the adenylate cyclase enzyme, that generates cAMP from ATP, thus, raising intracellular cAMP levels. Notably, cAMP signaling, through the PKA-dependent and/or -independent pathways, is very relevant to cancer and its targeting has shown a number of antitumor effects, including the induction of mesenchymal-to-epithelial transition, inhibition of cell growth and migration and enhancement of sensitivity to conventional antitumor drugs in cancer cells. Here, we describe some features of cAMP signaling that are relevant to cancer biology and address the state of the art concerning the natural cAMP elevating compound forskolin and its perspectives as an effective anticancer agent. J. Cell. Physiol. 232: 922-927, 2017. © 2016 Wiley Periodicals, Inc.

Activation of endogenous anti-inflammatory mediator cyclic AMP attenuates acute pyelonephritis in mice induced by uropathogenic Escherichia coli

The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells.

Beta-1 selective adrenergic antagonist landiolol and esmolol can be safely used in patients with airway hyperreactivity

This study was undertaken to clarify the effects of esmolol and landiolol, beta-1 selective adrenergic antagonists, on hyperreactive airways in both ovalbumin-sensitized guinea pigs and asthmatic patients. In the animal study, asthma was induced by ovalbumin. After control acetylcholine responses for total pulmonary resistance (Raw) and dynamic lung compliance (Cdyn) were obtained, the animals received propranolol, esmolol, or landiolol, and the same protocol was again performed. Sixty inpatients with coronary risk factors and asthma were enrolled in the human study. Under propofol anesthesia, the patients received saline, esmolol, or landiolol. To assess intubation-induced bronchoconstriction, the presence of wheezing was determined. The dose-response curves of Raw and Cdyn to acetylcholine were significantly elevated and declined in the ovalbumin-sensitized model compared with those in the control group. Neither esmolol nor landiolol had any effect on the acetylcholine-induced response curve in these sensitized animals. However, propranolol significantly enhanced Raw and reduced Cdyn in this model. Tracheal intubation increased the incidence of wheezing in asthmatic patients. However, there was no significant difference in the incidence of wheezing among these groups. The ultra-short-acting beta-1 selective adrenergic antagonists esmolol and landiolol can be safely used perioperatively in patients with airway hyperreactivity.

Cyclic AMP-regulated exocytosis of Escherichia coli from infected bladder epithelial cells

The superficial bladder epithelium is a powerful barrier to urine and also serves as a regulator of bladder volume, which is achieved by apical exocytosis of specialized fusiform vesicles during distension of the bladder. We report that type 1 fimbriated uropathogenic Escherichia coli (UPEC) circumvents the bladder barrier by harboring in these Rab27b/CD63-positive and cAMP-regulatable fusiform vesicles within bladder epithelial cells (BECs). Incorporation of UPEC into BEC fusiform compartments enabled bacteria to escape elimination during voiding and to re-emerge in the urine as the bladder distended. Notably, treatment of UPEC-infected mice with a drug that increases intracellular cAMP and induces exocytosis of fusiform vesicles reduced the number of intracellular E. coli.

Effect of prophylactic bronchodilator treatment with i.v. carperitide on airway resistance and lung compliance after tracheal intubation

BACKGROUND

Lung resistance increases after induction of anaesthesia. We hypothesized that prophylactic bronchodilation with i.v. carperitide before tracheal intubation would decrease airway resistance and increase lung compliance after placement of the tracheal tube in both smokers and nonsmokers.

METHODS

Ninety-seven adults aged between 24 and 59 yr were randomized to receive i.v. normal saline (0.9% saline) (control) or carperitide, 0.2 microg kg(-1) min(-1) throughout the study. The 97 patients included smokers and nonsmokers. Thus the patients were allocated to one of the four groups: smokers who received normal saline (n=21), nonsmokers who received normal saline (n=27), smokers who received carperitide (n=19) or nonsmokers who received carperitide (n=30). Thirty minutes after starting normal saline or carperitide infusion, we administered thiamylal 5 mg kg(-1) and fentanyl 5 microg kg(-1) to induce general anaesthesia and vecuronium 0.3 mg kg(-1) for muscle relaxation. Continuous infusion of thiamylal 15 mg kg(-1) h(-1) followed anaesthetic induction. Mean airway resistance (R(awm)), expiratory airway resistance (R(awe)) and dynamic lung compliance (C(dyn)) were determined 4, 8, 12 and 16 min after tracheal intubation and compared between the four groups.

RESULTS

At 4 min after intubation, R(awm) and R(awe) were higher and C(dyn) lower in smokers than in nonsmokers in the control group. R(awm) and R(awe) were lower and C(dyn) higher in smokers in the carperitide group than in smokers in the control group. R(awm) and R(awe) were lower in nonsmokers in the carperitide group than in nonsmokers in the control group.

CONCLUSIONS

Marked bronchoconstriction occurred in the control groups (smokers and nonsmokers) 4 min after tracheal intubation. Prophylactic treatment with carperitide before induction of anaesthesia and tracheal intubation was advantageous, particularly in smokers.

Both milrinone and colforsin daropate attenuate the sustained pial arteriolar constriction seen after unclamping of an abdominal aortic cross-clamp in rabbits

We previously reported that unclamping of an abdominal aortic cross-clamp causes initial dilation of pial arteries followed by sustained constriction. Both milrinone and colforsin daropate have a vasodilator action, and both have been used in such critical conditions as abdominal aortic aneurysmectomy. We measured cerebral pial arteriolar diameters using a rabbit closed cranial window preparation before (baseline) and 15 min after the start of an IV infusion of 0.9% saline (control group), milrinone, or colforsin daropate (0.05 and 0.5 microg . /kg(-1) . min(-1)) (pre-clamp), just after aortic clamping, 20 min after clamping, and at 0 to 60 min after unclamping. In the control group, a significant decrease in diameter persisted for at least 60 min after unclamping (maximum, -15% for large and -26% for small arterioles versus baseline). These values were significantly smaller after both doses of milrinone and the larger dose of colforsin daropate (-5% and -8%, 10% and 12%, and -2% and -5%, respectively vs baseline, at 60 min). In a second experiment, changes in regional cerebral blood flow and tissue oxygen tension reflected changes in vascular variables. Thus, sustained cerebral pial arteriolar constriction induced by aortic unclamping can be attenuated by IV milrinone or colforsin daropate.

Intravenous alprostadil, an analog of prostaglandin E1, prevents thiamylal-fentanyl-induced bronchoconstriction in humans

Prostaglandin (PG) E(1) relaxes airway smooth muscle in animals. However, no clinical data have been published on the bronchorelaxant effects of IV alprostadil, an analog of PGE(1). We have described experimental thiamylal-fentanyl-induced bronchoconstriction in humans; we now report the effect of IV alprostadil on thiamylal-fentanyl-induced bronchoconstriction. Thirty-two patients were allocated randomly to a control group (n = 16) and alprostadil group (n = 16). Anesthesia was induced with thiamylal 5 mg/kg and vecuronium 0.3 mg/kg and maintained with a continuous infusion of thiamylal 15 mg. kg(-1). h(-1). The lungs of the patients were ventilated with 50% nitrous oxide in oxygen. Twenty minutes after the induction of anesthesia, patients in the control group were given a continuous infusion of normal saline 20 mL/h, and those in the alprostadil group received a continuous infusion of alprostadil 0.2 micro g. kg(-1). min(-1) (20 mL/h), both for 60 min. Both groups were then given fentanyl 5 micro g/kg. Systolic and diastolic arterial blood pressure, heart rate, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured at the baseline, just before the fentanyl injection (T30), at three consecutive 6-min intervals after fentanyl injection (T36, T42, and T48), and 30 min after fentanyl injection (T60). Baseline Rawm, Rawe, and Cdyn values were comparable between groups. In the control group, both Rawm and Rawe were significantly increased at T36-60, and Cdyn was significantly decreased at T36-60 compared with the baseline. Patients given alprostadil showed no change in Rawm, Rawe, or Cdyn at T36-60. Thus, IV alprostadil seems to have a bronchodilator effect in humans.

IMPLICATIONS

IV alprostadil, an analog of prostaglandin E(1), prevents thiamylal-fentanyl-induced bronchoconstriction in humans. This finding suggests that IV alprostadil has a bronchodilator effect.

The effect of inhaled colforsin daropate on contractility of fatigued diaphragm in dogs

We studied the effect of inhaled colforsin daropate, a water-soluble forskolin derivative, on the contractility of fatigued diaphragm in dogs. Animals were divided into 3 groups of 8. In each group, diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20-Hz stimulation applied for 30 min. Immediately after the end of the fatigue-producing period, Group 1 received inhaled vehicle, Group 2 received inhaled colforsin daropate 0.1 mg/mL, and Group 3 received inhaled colforsin daropate 0.2 mg/mL. We assessed diaphragmatic contractility by transdiaphragmatic pressure (Pdi). After fatigue was produced, in each group, Pdi at low-frequency (20-Hz) stimulation decreased from baseline values (P < 0.05), and there was no change in Pdi at high-frequency (100-Hz) stimulation. In Groups 2 and 3, during colforsin daropate inhalation, Pdi at both stimuli increased from fatigued values (P < 0.05). The increase in Pdi was significantly larger in Group 3 than in Group 2. The integrated electrical activity of the diaphragm did not change in any group. We conclude that inhaled colforsin daropate causes an increase in contractility of fatigued canine diaphragm in a dose-related fashion.

IMPLICATIONS

Diaphragmatic fatigue may contribute to the development of respiratory failure. Inhaled colforsin daropate improves, in a dose-dependent manner, the contractility of fatigued diaphragm in dogs.

Intravenous nicorandil prevents thiamylal-fentanyl-induced bronchoconstriction in humans

OBJECTIVE

Nicorandil has a hybrid property between nitrates and potassium channel openers and has been reported to cause a concentration-dependent relaxation of isolated guinea pig trachealis. Experimental asthma in a guinea pig model was also inhibited by nicorandil. However, no clinical data on the bronchorelaxant effects of this drug have been published. The aim of this study was to investigate whether intravenous nicorandil prevents thiamylal-fentanyl-induced bronchoconstriction.

DESIGN

Double-blind, prospective, placebo-controlled, randomized study.

PATIENTS

A total of 36 patients were randomly allocated to two groups: a control group (n = 18) and a nicorandil group (n = 18).

INTERVENTIONS

Intravenous administration of nicorandil or a placebo (normal saline).

MEASUREMENTS AND MAIN RESULTS

Anesthesia was induced with 5 mg/kg thiamylal and 0.3 mg/kg vecuronium. A continuous infusion of 15 mg x kg(-1) x hr(-1) thiamylal was then used to maintain the anesthesia. Controlled ventilation was maintained, delivering 50% nitrous oxide in oxygen. At 20 mins after the induction of anesthesia, the control group patients were given a 6 mL/hr continuous infusion of normal saline and the nicorandil group patients were given a 6 mg x hr(-1) (6 mL/hr) continuous infusion of nicorandil for 60 mins. At 30 mins after the start of the study, both groups received a 5-microg/kg dose of fentanyl. Systolic and diastolic arterial pressure, heart rate, mean airway resistance, expiratory airway resistance, and dynamic lung compliance were measured for the baseline condition, just before the administration of fentanyl (T30), at three consecutive 6-min intervals after the fentanyl injection (T36, T42, and T48) and 30 mins after the fentanyl injection (T60). Both groups had comparable baseline values for mean airway resistance, expiratory airway resistance, and dynamic lung compliance. In the control group, both mean airway resistance and expiratory airway resistance increased significantly at T36-60, compared with the baseline values, and dynamic lung compliance decreased significantly at T36-60, compared with the baseline value. In the nicorandil group, no changes in mean airway resistance, expiratory airway resistance, or dynamic lung compliance occurred at T36-60.

CONCLUSIONS

Our observations suggest that the intravenous administration of nicorandil has a bronchodilator effect in humans.