Evaluation of PDE4 inhibition for COPD

Targeting type 4 phosphodiesterase (PDE4) for treatment of COPD has multilevel benefits to patients by reducing inflammation, relieving bronchoconstriction, and improving pulmonary circulation. The isoenzyme-specific narrow spectrum PDE4 inhibitors such as cilomilast and roflumilast may have limited clinical efficacy in managing severe and very severe COPD. Development of dual therapy by combining PDE4 inhibition with Ca2+ channel antagonism may introduce an effective novel armory for physicians to manage patients with severe COPD

TJ-41 Induces Apoptosis and Potentiates the Apoptotic Effects of 5-FU in Breast Cancer Cell Lines

Recent studies suggest that TJ-41, a herbal drug, possesses chemotherapeutic effects. Accordingly, this study was undertaken to investigate the anticarcinogenic effects of TJ-41 on human breast cancer cells lines. TJ-41 inhibited the proliferation of human breast cancer cell lines dose dependently. Flow cytometric analysis showed that this decrease in DNA synthesis is to be associated with induction of apoptosis. In both cell lines, apoptosis was abolished by caspase-9 inhibitor Z-LEHD-fmk but was weakly inhibited by caspase-8 inhibitor Z-IETD-fmk, indicating that caspase-9 activation was involved in TJ-41 induced apoptosis. Additionally, TJ-41 stimulated phosphorylation of c-Jun NH2-terminal kinase (JNK) and pretreatment of breast cancer cells with JNK inhibitor SP600125 completely abolished TJ-41 induced apoptosis. Our data also demonstrate that combined treatment of TJ-41 and 5-FU significantly potentiates the apoptotic effects of 5-FU in both breast cancer cell lines. Taken together, these data suggest that TJ-41 might provide a novel chemotherapeutic treatment for breast cancer

Tai Chi-induced Audible Bowel Sounds: An Indication of the Enhancement on the Parasympathetic Nervous System

Tai Chi movements are unique exercise that can improve cognition, strength somatomotor coordination, and enhance autonomic nerve regulation on internal organ function. The mild increase in heart rate and/or slight sweat during and after practicing Tai Chi clearly indicates the activation of the sympathetic nervous system. There is lack of evidence to show that Tai Chi exercise enhances the activity of parasympathetic nervous system (vagus nerve) though it is claimed that practicing Tai Chi can enhance vagal modulation. It is known that increase in the vagus nerve output reduces stress and cultivate body wellbeing. This study documents that Tai Chi exercise indeed activates parasympathetic nervous system by recording the bowel sounds using an audio recorder (Sony digital voice recorder ICD-PX Series) and analyzing the data using NCH software (WavePad audio editor). The heart rate was simultaneously recorded using a fingertip pulse oximeter (Zacurate Pro Series 500DL) during performing Tai Chi exercise. All the data was repeatedly collected from one Tai Chi performer (Master level) in a study period of 3 months. A total of 30 recordings were used to carry out the analysis. The audible bowel sounds occurred when the performer started to do the Ready-Movement of Yang-style Tai Chi. These Tai Chi induced- bowel sounds lasted from the beginning to the end of a set of movements (3-5 min for the 24-Short-Form or 12-15 min for the 88-Long- Form). The frequency of sounds was in a range of 0.2 to 3.5 Hz. The average number of the bowel sounds was approximately 2.5 sounds per Tai Chi Move. The intensity and frequency of the bowel sounds are not related to the change of the performer’s heart rate. In comparison, sit-down meditation or deep squat exercise did not cause any changes in the bowel sounds. According to the autonomic innervation of the GI tract, increase of bowel movement (sound) is mediated by parasympathetic nervous system activity. These results provide solid evidence that Tai Chi practice can simultaneously exercise the somatic motor system, the sympathetic nervous system and the parasympathetic nervous system. The enhancement of parasympathetic nervous system differentiates Tai Chi from other modalities of exercise

Novel approaches to using PDE4 inhibitors for antihypertensive therapy

Phosphodiesterase (PDE)4 inhibitors are effective vasodilators. In addition to the treatment of asthma and other inflammatory diseases, such as chronic obstructive pulmonary disease, wide-spectrum PDE4 inhibitors may also be developed for use in antihypertensive therapy, especially in patients with impaired renal function and elevated pulmonary arterial pressure. Rational approaches to overcoming the intrinsic emetogenic response associated with PDE4 inhibition are discussed, and a dual-action drug development that incorporates L-type Ca2+ channel antagonism and selective PDE4 inhibition is proposed. The potential for research and development of such a dual-action agent should eventually provide healthcare professionals with a new category of therapeutic options with which to attempt to combat hypertension

High performance liquid chromatographic analysis of MS23 piperidine analog MSP001 in rat plasma

MSP001 is a newly synthesized piperidine analog of the lead antihypertensive compound MS23 that dually targets cAMP-specific type 4 phosphodiesterase and L-type calcium channels. We validated an analytical protocol for MSP001 in rat plasma using high performance liquid chromatographic method. A C18 column and a phosphate/acetonitrile buffer were used to perform the chromatographic separation. UV detection was carried out at 307 nm, a wavelength at which an absorption peak was detected for this group of compounds. The calibration curve for MSP001 was linear in the range from 25 to 10,000 ng/ml. The limit of quantification (LOQ) was 25 ng/ml. The results demonstrate that this method has high linearity (R = 0.99995), compound specificity, and acceptable precision/accuracy. The protocol is suitable for in vivo pharmacokinetic studies on the compound. © 2006 Elsevier B.V. All rights reserved

Mechanism of the negative inotropic effect of adenosine in guinea pig atrial myocytes.

The ionic basis of the negative inotropic effect of adenosine on guinea pig atrial myocytes was studied. Membrane potentials and currents were measured using a whole cell patch-clamp technique. The contractility was assessed by video quantitation of cell twitch amplitude. Adenosine shortened action potential duration [measured at 90% repolarization (APD90)] and decreased twitch amplitude in a concentration-dependent manner. The maximal effects of adenosine (100 microM) were to reduce APD90 from 102 +/- 14 to 34 +/- 8 ms (n = 11) and twitch amplitude from 4.3 +/- 0.9 to 1.5 +/- 0.4 microns (n = 8). The concentration of adenosine that caused one-half of the maximal reductions of twitch amplitude and of APD90 was 0.6 microM. Reductions in APD90 and in twitch amplitude were parallel and highly correlated (r = 0.98). Decreases in twitch amplitude by adenosine could be mimicked by application of voltage-clamp pulses with durations similar to the durations of action potentials in the presence of adenosine. Clamp pulse could reverse adenosine-induced but not cadmium chloride-induced decreases in twitch amplitude. Adenosine activated the inwardly rectifying K+ current (IK,Ado), but did not significantly decrease the L-type Ca2+ current (ICa,L). Adenosine reduced the effects of BAY K 8644 on APD90 and twitch amplitude but did not attenuate the BAY K-induced increase in ICa,L. The effects of adenosine on APD90 and twitch amplitude could be reversed after activation of IK,Ado was inhibited by intracellular application of cesium and tetraethylammonium chloride.(ABSTRACT TRUNCATED AT 250 WORDS

Validation of HPLC analysis method of a novel antihypertensive agent MS23 in rat plasma

MS23 is a vasodilator with unique dual action pharmacological profile to inhibit type 4 PDE and antagonize L-type calcium channels. We validated an analytical protocol for MS23 in rat plasma using high performance liquid chromatography (HPLC). A C18 column and a phosphate/acetonitrite buffer were used for chromatographic separation. UV detection was performed at 307 nm. The calibration curve for MS23 was linear in the range from 50 to 10,000 ng/ml. The limit of quantification (LOQ) was 50 ng/ml. The results demonstrate that the method has linearity (R = 0.9989), specificity, and acceptable precision/accuracy. This method is simple, economic, and sufficient for in vivo pharmacokinetic studies on the compound. © 2005 Elsevier B.V. All rights reserved

Alcohol abrogates intracellular Ca2+ elevation by angiotensin II and ATP in cultured rat astrocytes

Intracellular Ca2+ of astrocytes can be mobilized by many neurotransmitters and neuromodulators. We studied whether the regulation of intracellular Ca2+ concentration ([Ca2+]i) by angiotensin II and ATP is altered by alcohol treatment in cultured rat hippocampal astrocytes. Pulsatory [Ca2+]i elevation as measured by Fura-2 fluorescence can be repeatedly induced when the cells were challenged with Angiotensin II (30 nM) and ATP (3 µM) in the absence of ethanol. Peptidergic neurotransmitter angiotensin II produced a peak and a prolonged plateau elevation in [Ca2+]i. In comparison, purinergic neuromodulator ATP caused a brief and steeper Ca2+ peak with a much faster recovery phase (i.e., lack of prolonged plateau elevation of [Ca2+]i. Ethanol treatment (10 - 20 mM) of the cells for 5 to 10 min itself did not cause any detectable [Ca2+]i change. However, in the presence of alcohol (20 mM, approximately equal to 0.12% plasma alcohol level), both the peak and the plateau phases of [Ca2+]i elevation by angiotensin II (30 nM) and ATP (3 µM) were completely abolished. The ethanol intoxicated cells did not respond to higher concentration of angiotensin II (300 nM) but were able to generate a blunted [Ca2+]i elevation when challenged with 1 mM ATP. These results demonstrate that ethanol alters the regulation of [Ca2+]i by neurotransmitters and neuromodulators in astrocytes, which may play a significant role in alcohol intoxication

Preclinical pharmacokinetics and metabolism of MNP001, a piperidine analog of 3-carbamyl compounds

MNP001 is a newly synthesized 3-carbamyl-4-methylpyrrole analog with dual pharmacophores simultaneously to inhibit phosphodiesterase type 4 (PDE4) and to antagonize L-type calcium channels. The physicochemical properties of MNP001, including solubility, pKa, Log P, plasma protein binding and plasma/blood partitioning, were determined to support the pharmacokinetic characterization. The preclinical pharmacokinetic parameters were determined in an in vivo rat model and the metabolic pathways of MNP001 were characterized by incubating the compound in vitro in rat or human microsomes/supersomes cocktails. MNP001 was found to have a low solubility in simulated intestinal fluid but a high solubility in simulated gastric fluid. MNP001 is a highly lipophilic compound with a Log P value greater than 4. MNP001 was highly bound to the plasma protein and had an uneven partition between red blood cells and plasma. MNP001 exhibited a rapid absorption, broad distribution, slow systemic clearance and a low but pharmacologically relevant oral bioavailability in rats. The low oral bioavailability was possibly caused by the low aqueous solubility of MNP001 in the gastrointestinal tract. However, 8 h after oral dosing, the mean plasma level of MNP001 was able to remain about 2-fold greater than the minimum effective concentration. The major metabolite of MNP001 was defined as a tetrahydropyridine product (MNP001-M4) of CYP3A4-mediated phase I oxidation. The possibility that the major metabolite MNP001-M4 may have a comparable antihypertensive efficacy to MNP001 needs to be studied. Copyright © 2010 John Wiley & Sons, Ltd