Effect of bitter kola (garcina kola), alligator pepper (melegueta pepper), ions and drugs on toad (bufo regularis) heart contraction.

EFFECT OF BITTER KOLA (GARCINA KOLA), ALLIGATOR PEPPER (MELEGUETA PEPPER), IONS AND DRUGS ON TOAD (BUFO REGULARIS) HEART CONTRACTION.

CHAPTER 1

INTRODUCTION

• BACKGROUND OF THE STUDY

Toad and toad are two closely related amphibian species. However, toads are more adapted to living on land than the wet habitats in which toads reside. In land habitats, the volumes of toad body fluid and blood change with large ranges between rain and dry seasons( BORAL ,2010) or with different heat exposures.The heart of toad apparently adapts well to working with a big range of blood volume changes.The function of the vertebrate circulatory system is critically dependent on and closely regulated by the volume of circulating blood( Peitzma,2015). Decreases of blood volume such as that in humans during hemorrhagic shock would result in decreased cardiac output due to both decreased ventricular filling and increased peripheral arterial resistance from the compensatory increase in sympathetic tone (4). Therefore, to understand the mechanism(s) by which the toad heart is able to cope with the drastic decrease in blood volume such as that occurs during dry season  or under experimental conditions and sustain cardiac output is of physiological and medical importance.

A foundation of heart function is the myofilament proteins that form the contractile machinery in cardiac muscle (GORDON, 2000). Comparative studies of the myofilament contractile and regulatory proteins in the hearts of toad and toad are valuable in revealing the molecular basis of the functional feature of toad cardiac muscle.

The heart of the toad has three chambers, one ventricle and two atria. Blood leaves the heart from the ventricle through a single truncus arteriosus which is short and soon branches into two aortic arches which loop left and right and dorsal to the heart to rejoin as a single aorta in the mid dorsal region of the body cavity. Each aortic arch has a branch leading to the lungs and skin where oxygenation occurs. Carotid arteries also branch off the aortic arches and supply the head region. Veins bring blood to the left and right atria. Both atria then empty into the single ventricle. Blood from the ventricle thus enters either the pulmonary or body circulation.

Because there is only a single ventricle there is some mixing of oxygenated and deoxygenated blood. Ventricular folds prevent a complete mixing of the arterial and venous blood.

 

Excitation of the toad heart heart is myogenic, that is, contraction of the heart originates within the muscle itself. In Amphibians, such as the toad, the pacemaker is the sinus venosus, an enlarged region between the vena cava and the right atrium. This the cells of the pacemaker are termed “leaky”, meaning that calcium ions leak into the cells. Leaking of positive ions causes a slow depolarization to threshold, thus initiating an action potential that quickly spreads throughout the muscle. The atria are very conductive, and the action potential spreads readily across these two chambers. The major route for the transmission of action potentials from the SA node to the ventricle(s) is by way of a set of modified conductive muscle cells that compose the bundle of His embedded in the septum separating the two atria. In animals with a four-chambered heart, it continues through the septum separating the two ventricles.

 

 

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The cells that are most leaky to calcium initiate action potentials more frequently and set the rate of contraction for entire heart structure. Each region of the heart has its own intrinsic rate of beating.

 

Nervous control of the heart is primarily regulated by medulla of the brain, and the heart is innervated by both sympathetic and parasympathetic nerve fibers that terminate at the SA node. The neurotransmitters released by these nerves affect both heart rate (chronotropic effects; chronos = time) and the strength of contraction (inotropic effects), by influencing the timing and magnitude of ion currents across the cell membrane.

 

The vagus nerves contain parasympathetic cholinergic neurons that release acetylcholine at their terminals. This neurotransmitter binds with muscarinic receptors and initiates many effects, including a cascade that increases the number of K+ channels in the open position; thus keeping the membrane near the equilibrium potential for K+ and making depolarization more difficult.

 

The sympathetic cardiac nerves contain adrenergic neurons that release epinephrine or norepinephrine, depending on the species. (Amphibians release both of these neurotransmitters.) These neurotransmitters bind b1 adrenergic receptors at both the SA node and in the myocardium. This binding can cause a variety of effects, including an increased inward flux of Ca++ into the cell.

 

The function of the muscarinic and adrenergic receptors in the heart can be revealed by examining how the heart responds when these receptors are activated or inactivated. Compounds that activate a receptor are called agonists, while compounds that inactivate a receptors by binding to it are called antagonists. Most medications used in the treatment of heart disorders are antagonists for either muscarinic or b-adrenergic receptors.  The study is the effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction.

 

• STATEMENT OF THE PROBLEM

The problem confronting the study is the effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction. The heart of toad apparently adapts well to working with a big range of blood volume changes.The function of the vertebrate circulatory system is critically dependent on and closely regulated by the volume of circulating blood( Peitzma,2015). Decreases of blood volume such as that in humans during hemorrhagic shock would result in decreased cardiac output due to both decreased ventricular filling and increased peripheral arterial resistance from the compensatory increase in sympathetic tone (4). Therefore, to understand the mechanism(s) by which the toad heart is able to cope with the drastic decrease in blood volume such as that occurs during dry season  or under experimental conditions and sustain cardiac output is of physiological and medical importance

 

 

• OBJECTIVE OF THE STUDY

The main objective of the study is the effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction.The specific objective include

To determine the nature and significance of kola nuts

To determine the nature and significance of alligator pepper

To determine the nature and significance of ions

To dertermine the effect of effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction

• SIGNIFICANCE OF THE STUDY

The mechanism(s) by which the toad heart is able to cope with the drastic decrease in blood volume such as that occurs during dry season  or under experimental conditions and sustain cardiac output is of physiological and medical importance. The study determines  the effect of effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction

 

• SCOPE OF THE STUDY

The study focuses on appraising the effect of bitter kola ,  alligator  pepper,  ions on toad heart contraction.It examines the nature and significance of bitter kola ,  alligator  pepper,  ions  and there effect on toads heart contraction

 

 

• LIMITATION OF THE STUDY

The study was confronted with the following constraints

1.TIME; The researcher was faced with other academic activities in the course of conducting the study

2. LOGISTICS; The researcher is was also confronted with issues relating to logistics in the course of conducting the study
3. MATERIALS. Limited materials were available for conducting the study

 

• DEFINITION OF TERMS

KOLA NUT  DEFINED

Kola nut  (a name sometimes also used for G. afzelii) is a species of flowering plant belonging to the Mangosteen genus Garcinia of the family Clusiaceae (a.k.a. Guttiferae).

 

IONS DEFINED

ion is defined as an atom or molecule that has gained or lost one or more of its valence electrons, giving it a net positive or negative electrical charge. In other words, there is an imbalance in the number of protons (positively charged particles) and electrons (negatively charged particles) in a chemical species.

ALLIGATOR PEPPER DEFINED

Aframomum melegueta (Alligator pepper) Alligator pepper (Aframomum melegueta) also known as grains of paradise, is a tropical perennial herb of genus Aframomum and family, Zingiberaceae also known as the ginger family (Bamidele, 2019). Alligator pepper is greatly utilized by many countries including Nigeria for diverse puposes. For instance, it is a common item used for traditional sacrifices and other religious rites. Also, several uses of alligator pepper have been reported in the literature and this includes its efficacy in controlling larvae of Spodoptera littoralis and Egyptian cotton leaf worm and also important crop pests such as the diamond back moth Plutella xylostella L. (Ntonifor et al., 2006; 2010). Alligator pepper has immense medicinal importance. The seed extract heals wounds and invigorates the immune system against diseases (Ntonifor et al., 2010)

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