Related Experiment Video
Updated: Aug 25, 2026

Microelectrode Impalement Method to Record Membrane Potential from a Cannulated Middle Cerebral Artery
Published on: July 2, 2019
A bradykinin potentiating peptide from Egyptian cobra venom strongly affects rat atrium contractile force and
Muhammad A M El-Saadani1, Muhammad F El-Sayed
1Department of Biochemistry, Faculty of Science, Alexandria University, Alexandria, Egypt. El_saadaniM@hotmail.com
Abstract:
Peptide fractions were isolated from venoms of the Egyptian snake Naja haje haje (cobra BPP) and the scorpions Buthus occitanus (BPP(B)) and Leirus quenquestriatus (BPP(L)). The pharmacological effects of these peptides were bioassayed and showed bradykinin potentiating activities. Amino acid analysis revealed that 14 amino acids contribute to the structure of BPP(B) and 16 for BPP(L), while cobra BPP was composed of 15 amino acids. Treatment of rat atrial preparations with 50 microg/ml of cobra BPP caused a significant reduction (P<0.001) in myocardial force. Elevation of extracellular calcium concentration from 1.25 to 5 mM antagonized the effect of cobra BPP in a way that restored the atrial force development. Na(+)-channel blockers did not change the force development at 5 mM Ca(2+). Experiments with (45)Ca revealed that Ca(2+) uptake of cobra BPP treated atria was 0.52+/-0.07 microM/g wet mass and the force at the end of the uptake period was 55.0+/-2.0%. The corresponding values for non-treated preparations were 0.56+/-0.04 microM/g and 92.0%+/-3.0%, respectively. Our results revealed that cobra BPP did not exhibit any effect on Ca(2+) uptake by rat atrial preparations, but strongly affected cellular Ca(2+) regulation.
Related Concept Videos
Antihypertensive Drugs: Action of Calcium Channel Blockers
Antihypertensive Drugs: Angiotensin II Receptor Blockers
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
G-Protein Gated Ion Channels
Sensory organs,...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...

