Different Drugs on Gastrointestinal Tract Motility - Assignment Example

Abstract This experiment is a demonstration of functional roles of different drugs on the gastrointestinal tract motility by of a section of guinea pig colon. This is based on the observation that some drugs have the capability to affect the manner in which various tissues and organs in the body function. In order to achieve this objective, effects of different drugs such as morphine on the contraction of the ileum invoked by trans-mural stimulation are investigated. This is achieved by increasing the concentration of morphine and naxolone in the tissues in which experiments are carried out. The results include time taken for a pellet of morphine and naloxone to travel a distance of 7 cm in the colon. These results are used to draw graphs that are used for interpretation of the results of the research. TABLE OF CONTENTS Abstract 1 Introduction 2 Objectives 2 Method 2 Results 3 Discussion 8 Summary of the main Findings 9 Introduction 2 9 Objectives 2 9 Methods 2 10 Results 2 10 Discussion 2 11 Summary of the main findings 2 11 References 12 Appendix 12 Experiment 1 Title: Title: A demonstration to investigate some sites of drug action on gastrointestinal tract motility Introduction Pharmacy involves provision of medicines aimed at treating a particular aliment. However, it is necessary that pharmacists understand the effects of the drugs on the functioning of different systems in the body. An example of part of the body where such effects are experienced is the ileum section of the small intestines (Schatzberg and Nemeroff 2009). Particular types of drugs have the ability to produce either contraction or relaxation of muscles. Such changes can result when the receptors located on an excitable membrane interact or when there is a direct action on the surface of smooth muscle cells. An example of a receptor found in the intestinal smooth muscles is that which is associated with parasympathetic nervous system that contributes to gut contraction and those associated with sympathetic nervous system that contributes to gut relaxation. It is also possible to induce smooth muscles contraction in a direct manner through administration of potassium chloride that results into an increase in extracellular concentration of potassium ions, hence resulting into a disrupted trans membrane potential and finally depolarization (Dressman and Krämer 2005). Objectives Some of the objectives of this experiment include the following: To investigate requirements for maintaining the functions of ex vivo tissue To understand pharmacological regulation of GI motility To understand the pharmacological and physiological regulation of autonomic control of the gut Method A piece of guinea pig ileum was prepared for transmural stimulation. A pulse of 0.5ms, a frequency of 0.1Hz was used and these values were increased on gradual basis until a measurable contraction was obtained. This was followed by addition of morphine (10mM stock) or atropine (10mM stock) at the bath with a final concentration of 1µM. The pulse width on the stimulator was increased until a contraction was recorded. This resulted into a selective stimulation of the muscles. Morphine was applied in the presence of naxolone or atropine and the effects on muscle contraction was observed and recorded. 50mM KCl bath was applied. The second part of the experiment involved an investigation of the effects of various drugs on colonic motility. A freshly dissected piece of guinea pig colon was placed in a long organ bath. Small incisions were made in both ends of the colon and the tissue pinned to the slygard-lined bath. The preparation was continuously perfused with warmed Krebs buffer solution. An epoxy-coated pellet was inserted into the proximal end of the colon by use of a blunt glass probe. Pellet motility through the bowel was recorded using a stop watch. 1µM morphine was added to the colon and the effects of the motion of the pellet were determined. The effect of further adding naloxone to the tissue where morphine was added was also investigated. Data that was collected during the experiment includes changes in tissue activity when various concentrations of morphine and naloxone were added. A three-minute dose cycle was used to investigate the effects of morphine Ach induced responses. It was suggested that the starting concentration of morphine to be used is the one that contributed to inhibitory effect on trans mural stimulation conducted in the GI practical. The suggested starting concentration of naloxone was the dose that resulted into a reverse of inhibition of morphine on transmural stimulation carried out in the GI motility case. Results The following data was collected and corresponding graphs drawn. a. Molar Concentration of morphine versus contractile response of field stimulated tissue in (mm) Concentration of Morphine (M) Contractile response (mm) 1 ×10-10 92 3 ×10-10 91 1 ×10-9 90 3 ×10-9 88 1 ×10-8 82 3 ×10-8 64 1 ×10-7 36 3 ×10-7 30 1 ×10-6 27 1 ×10-6 26 1 ×10-5 24 Figure 1: Molar Concentration of morphine versus contractile response of field stimulated tissue in (mm) a. The logarithm of molar concentration of morphine versus contractile response of field stimulated tissue in (mm). Logarithm of Molar Concentration of Morphine (M) Contractile response (mm) -10 92 -9.52 91 -9 90 -8.52 88 -8 82 -7.52 64 -7 36 -6.52 30 -6 27 -5.52 26 -5 24 Figure 2: The logarithm of molar concentration of morphine versus contractile response of field stimulated tissue in (mm). Concentration of Morphine (M) % Relaxation of stimulated tissue 1 ×10-10 0 3 ×10-10 1.086 1 ×10-9 2.222 3 ×10-9 4.347 1 ×10-8 11.111 3 ×10-8 30.434 1 ×10-7 60.869 3 ×10-7 67.391 1 ×10-6 70.652 1 ×10-6 71.739 1 ×10-5 73.913 Figure 3: Concentation of Morphine vs % Relaxation of stimulated tissue Logarithm of Molar Concentration of Morphine (M) % Relaxation of stimulated tissue -10 0 -9.52 1.086 -9 2.222 -8.52 4.347 -8 11.111 -7.52 30.434 -7 60.869 -6.52 67.391 -6 70.652 -5.52 71.739 -5 73.913 Figure 4: Logarithm10 of Molar concentration vs %relaxation of tissue When morphine was added, it was observed that there was a regular fluctuation in the intra-luminal pressure. This effect was reduced when naxolone was added. Morphine-induced waves were maintained at a normal level but occasionally, there was a reduction in amplitude or frequency. The time taken for the pellet to travel a distance of 7 cm was determined for various concentrations of morphine as shown below. Treatment Time taken for pellet to travel 7 cm (s) Control 44.5 Control 35.8 10 µM morphine No movement in 9 minutes 10 µM morphine No movement in 9 minutes 1 µM naloxone 19.4 1 µM naloxone 19.6 Figure 5: pellet motility in the presence of Morphine and on addition of naxolone Discussion Field stimulation resulted into contraction of the ileum at low frequencies of between 0.125 to 1.0Hz, the spontaneous contractions being incorporated into the response. At frequencies greater than 1.0Hz, there was a reduction in responses. The purpose of adding atropine in the physiological solution was to optimize relation responses (Center for Food Safety and Applied Nutrition 2004). Morphine inhibited the contractile response of the ileum to electrical stimulation of the spinal motor as well as contributing to inhibition of motor responses to the field stimulation (Renzenbrink 1988). The graph shows that when 0.1nM of morphine was added, no observation was made initially, but when the concentration was increased to 10µM, there was no motion of the pellet in the colon for 9 minutes. This is because the contraction of the colon was inhibited by the addition of morphine (Dressman and Krämer 2005). Thus morphine can be concluded to be a drug that inhibits the contraction of the colon thus inhibiting motility of food pellets. The effect of naxolone is that it reduced the activity of morphine by enabling muscle contraction to electrical stimulation. Morphine contributed to inhibited contraction of the colon thus inhibiting the motility of the pellet through the colon. When naxolone was added, the effect of morphine was inhibited and the motility o the pellet along the colon was restored. Naxolone acts in antagonistic manner to contribute to a gradual increase in contractility when concentration of naloxone was increased successively. However, atropine showed a significant impact on Ach-induced contraction. When filed stimulation takes place, morphine affects concentration of Ca+2 thus affecting the release of Ach at synaptic cleft (Molema 2001). However, in the Ach induced contraction, the availability of Ach in the M3 receptors results into initiation of contraction, indicating no significant effect of morphine on contraction of the ileum. Summary of the main Findings The main findings of this study included the following: i. Morphine inhibits contractile motion of the ileum ii. Morphine reduces pellet motility in the colon by inducing contractions which result into a series of irregular contractions and relaxations to normal condition. iii. Naxolone inhibits the effects of morphine iv. Morphine and naxolone do not affect Ach induced contractions of the ileum compared to the effects of field contraction. Experiment 2: Title 2: Analysis of the effects of a range of drug molecules on evoked contractions of the guinea pig ileum Introduction 2 Drugs have the potential to induce changes in activities of cells by their actions on receptors. Such drugs are called antagonists. They bind to the receptors but do not contribute to any impact, rather than blocking the reach of the antagonist to the receptor. In this experiment, the effects of morphine, atropine and naxolone on a pig’s small intestines were investigated (Renzenbrink 1988). A detailed examination of the structure of the small intestines shows that it is a complex organ that contains layers of muscles and other plexii containing nerve cells that contribute towards nerves contraction. Objectives 2 The following were the objectives of this experiment: i. To demonstrate the interaction of drugs with functions of receptors in the ileum ii. To understand the concepts of agonists and antagonists with respect to the functioning of receptors of the ileum iii. To assess the student understands of the concepts of pharmacology. Methods 2 The tissue to be used was placed in a bath of volume 25ml. An electrode was passed through the lumen of the tissue Ach buffer of 1 X 10-8 M was added and the effects of atropine on Ach-induced responses was observed and recorded. Morphine at a concentration of 1mM (1 X 10-3 M) was added, atropine at a concentration of 0.1mM (1 X 10-4M) was added and finally naloxone at a concentration of 0.3mM (3 X 10-4 M) was also added. Data was collected using a powerlab system by use of a transducer attached to a computer system. Results 2 It was observed that when Acetylcholine (Ach) was added, ileum contraction was observed. It was also observed that when morphine was added, ileum contraction was inhibited. When atropine was added, ileum contraction was observed. The results of the contraction at various concentrations of the bath were recorded as shown below. Concentration Baseline (g) Peak 3 X 10-6 0.36g 1.25g 1 X 10-6 -0.14g 1.48g 3 X 10-7 -0.25g 1.91g 3 X 10-8 -0.02g 2.12g 1 X 10-8 -0.15g 2.11g Figure 6. Conentration of the bath against peak and baseline Discussion 2 Acetylcholine (Ach) contributes to ileum contraction by binding to receptors on the walls of the ileum. The receptors on the walls of the ileum activate phospholipase C (PLC), which contributes to hydrolysis of phospholipids in the cell membranes thus generating messengers. These messengers influence phosphorylation and regulation of calcium ions (Ca2+). The messengers activate membrane-bound protein kinase which phosphorylate different proteins and contribute to contraction of the walls of the ileum. The addition of naloxone to the field stimulated guinea pig ileum; it acts as an antagonist against morphine and prevents the possibility of binding of morphine to the walls of the intestines. Thus, when more naloxone is added, the response increases. When atropine is added, it is observed that there is a slight decrease in response but there is a gradual reduction in response as a result of antagonism of atropine to Ach receptor, which enhances ileum wall contraction. Summary of the main findings 2 The following are the main findings of this experiment: Addition of Acetylcholine (Ach) enhanced ileum contraction Addition of morphine inhibited ileum contraction Addition of atropine restored ileum contraction References Center for Food Safety and Applied Nutrition (U.S.). 2004. The bad bug book: Foodborne pathogenic microorganisms and natural toxins handbook. McLean, Va: International Medical Pub. Dressman, J. B., & Krämer, J. 2005. Pharmaceutical dissolution testing. Boca Raton: Taylor & Francis. Johnson, L. R. 1994. Physiology of the gastrointestinal tract. New York: Raven Press. Molema, G. 2001. Drug targeting: Organ-specific strategies. Weinheim [u.a.: Wiley-VCH. Renzenbrink, U. 1988. Diet and cancer: An anthroposophical contribution to cancer prevention. Steiner. Schatzberg, A. F., & Nemeroff, C. B. 2009. The American Psychiatric Publishing textbook of psychopharmacology. Washington, D.C: American Psychiatric Pub. Appendix Treatment Time taken for pellet to travel 7 cm (s) Control 44.5 Control 35.8 10 µM morphine No movement in 9 minutes 10 µM morphine No movement in 9 minutes 1 µM naloxone 19.4 1 µM naloxone 19.6 Read More